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    In This Issuen This ssueIn This Issue

    Editor

    MAHENDRA JAIN

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    July 2009

    Year—12 Issue—137

    C.S.V. / July/ 2009 / 533

    Regulars

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    C.S.V. / July / 2009 / 535 / 1A

    For welfare and progress, a life of discipline is very essential whether it be an individual, a group, a society or a nation. For that matter it may be a case of the world.

    It may be mentioned that for 

    want of a discipline, most of our country men appear dejected, pulled 

    down  or  without  any  enthusiasm. They 

    seem to be having no goal of life.

    It is a well known fact the three factors—Family, atmosphere, edu- 

    cational system and political thinking 

    go to form the personality of persons.

    In the family the individual learns to live in discipline, to obey elders and to lead a cooperative and tolerant 

    life. These things go a long way in 

    making the individual useful to the society and the nation. Aristotle has 

    rightly said that “State is an enlarged 

    form of the family.” The present deve- 

    lopment of civilization owes much to the good traditions and development 

    of the families from generation to 

    generation.

    To draw out the best, specially the latent powers of the child ought to be the main function of an edu- cational system. To make a perfect man of an individual has also always,been considered the chief aim of education. The aim of the education is the all round development of the individual. This, like the family, goes a long way in making the individual an useful instrument in giving proper and designed shape to the nation. The present system of education, which 

    is the legacy of the British rule has been only partially useful in this respect. Although many people find faults in the present system of education yet we will say that the present system has its own merits. In case otherwise it should not have produced big persons like Raja Ram Mohan Roy, Swami Vivekanand,Lokmanya Tilak, Mahatma Gandhi and others. Looking at different aspects of  the role in the development of the person and the state it may be very easily said that discipline in 

    family and education life has a great role to play in the formation of the person, society and the nation.

    In the present set up of the society, politics and political thinking have acquired top priority. From the personal life the national interests all depend on politics. We can easily say that the life of the nation has become politically biased Herbert Spencer had forseen the present conditions when he wrote, “You may leave politics, the politics will not leave you.” 

    The multi party system in our 

    country has made confusion worse 

    confounded. The main reason is that the party leaders have very little 

    sense of discipline, they have little respect for the declared objects of the party and are only running after 

    seeking pelf and power. The result is 

    that they are hardly making any social 

    or national progress and are fast loosing values of life.

    People are often heard to say 

    that the present politics has no place for the intelligent or the intellectual.

    They often are unpalatable meta- 

    phors for the political system. Be as it 

    may, the political life of the country has failed to make any contribution 

    for discipline of the people at large.

    We should pause a little to think 

    how far our family life, educational 

    system and political system have been successful in disciplining people and develop in them the human 

    quality. The answer may be dis- 

    appointing but we need not be dejected. History tells us that there 

    were times when things had gone 

    worse—But people of firm deter- mination led a life of strict discipline 

    and thus impacted their neighbour- 

    hood. In the modern times Mahatma 

    Gandhi has been a glaring example of such people. He by his personal 

    example made many persons to lead 

    a disciplined life which ultimately formed a big discipline party.

    Education means drawing out of 

    all latent powers and all round deve- 

    lopment of faculties of the human being. It means that certain rules and 

    regulations are to be followed where 

    proper education is concerned. This 

    is nothing but observing a certain discipline. On the path of meditation 

    or spirituality, some discipline, namely 

    Raj Yoga, Dhyana Yoga, Bhakti Yoga or Hath Yoga is to  be  followed. Where 

    development is concerned, discipline 

    plays a very important role.

    They say that humanity has 

    become civilized through discipline.We forget that the persons whom we 

    call natives or man of jungle also 

    follow certain  rules of conduct and are in a way leading a disciplined life. In 

    the community of abonimals, certain 

    rules of discipline and conduct are 

    followed. In short, where there is human society, there is discipline,

    because without it, no life is possible.

    When there is no discipline, there 

    is confusion, disorder and ultimately war, but in war also certain rules are 

    to be followed, the soldiers lead a 

    life of ‘do or die’ discipline and then fight the war. In short, in both, dis- 

    order and peace, discipline is indis- 

    pensable. Therefore, let us remember that discipline is the life blood of the 

    human society, without it, no life is possible.

    ●●●

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    T T H O U G H TS  FOR THE M O N  T H

    ❥ Everything appears coloured to the jaundiced eye.

    ❥ However clever you are, there is someone cleverer than you.

    ❥ If you don’t crack the shell, you can’t eat the nut.❥ Using threats of suspension as a major strategy for maintaining

    discipline does not go a long way.

    ❥ Sooner or later the man who wins is the man who thinks he can.

    ❥ Prefer a loss to a dishonest gain; the one brings pain at the mo-

    ment, the other for all time.

    ❥ The humblest citizen of all land, when clad in the armour of righ-teous cause, is stronger than all the hosts of error.

    ❥ To be vanquished and yet not surrender, that is victory.

    ❥ What you cannot say before your enemy, do not say before yourfriend.

    ❥ Criticism breeds criticism.

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    C.S.V. / July / 2009 / 537

    Rebirth of Hubble SpaceTelescope

    The Hubble space telescope, theobject of NASA’s fifth and the last

    servicing mission, is a veritable time

    machine that has revolutionalisedhumankind’s vision and comprehen-

    sion of the universe. Put into orbit at

    an altitude of 600 km by the shuttleDiscovery on April 25, 1990, Hubble

    has transmitted more than 7,50,000

    spectacular images and streams of

    data from the ends of the Universe,opening a new era. But the Hubble

    telescope, the fruit of a collaboration

    between NASA and the EuropeanSpace Agency, had a troubled start

    and did not become operational until

    three years after its deployment.

    Its lense in effect had to be fixed

    because of a flaw in its shape, a sen-

    sitive operation that was not carried

    out until 1993 in the first shuttle-borneservice mission, which installed

    corrective lenses. From that time o n

    Hubble space  telescope transmittedstupefying images of supernovas,

    gigantic explosions that marked the

    death of a star and revealedmysterious black holes in the centre

    of virtually all galaxies.

    Helping Hand : In this image taken fromNASA video, Hubble is captured by thespace shuttle Atlantis’ robotic arm as itbegins its mission to service the spacetelescope.

    Thanks to these observations,delivered with 10 times clarity of the

    most powerful telescopes on the

    Earth, the astronomers have been

    able to confirm that the Universe isexpanding at an accelerating rate and

    to calculate its age with greater

    precision as an estimated 13·7 billionyears. The universe’s accelerationis the result of an unknown force

    dubbed dark energy that consti-tutes three-quarters of the Universeand counterbalances the force of

    gravity. The rest of the cosmos is

    composed of five per cent visiblematter and about 20% shadow

    matter or anti-matter.

    Among the other discoveries,credited to Hubble, figures the detec-

    tion of the first organic molecule in

    the atmosphere of a planet orbiting

    another star and the fact that the

    process of formation of planets andsolar systems is relatively common in

    our galaxy, the Milky Way. Hubblealso has observed small proto-

    galaxies that were emitting rays of

    light when the Universe was less thana billion years old, the farthest back in

    time that a telescope has been able

    to peer so far.

    Eye in the sky : A few of the stunningimages taken by the Hubble space tele-scope over the years.

    In space, Hubble was capturedby the space shuttle Atlantis’ robotic

    arm as it began its mission to servicethe space telescope. Two astronautsMike Massimino and Mike Good

    emerged from the airlock of the

    shuttle Atlantis and began work on

    Space Telescope.

    In addition to the partial revival of

    the Advanced Camera for surveys,

    they installed two new scientific instru-ments and a crucial science computer

    as well as replaced gyroscopes and

    batteries to sustain the Observatory’s

    pointing and power systems. Theoverhauling prepared Hubble to

    search for the oldest and the most

    distant galaxies, map the large scalestructure of the Universe and study

    the planet forming processes around

    other stars.

    The two new installed instruments

    will enable Hubble to look out in timeas far as 500 to 600 million years

    after the Universe’s birth with the big

    bang.

    Closer to home, Hubble has

    observed radical changes in thedirection of Saturn’s winds and

    revealed that Neptune has seasons.

    Hubble has also examined mysterious

    lightning flashes on Jupiter and takenastonishing pictures of Mars.

    New York-Sized Ice ShelfCollapses in Antarctic

    An area of ice shelf, almost the

    size of New York City, broke into ice-

    bergs in April 2009 after the collapseof an ice-bridge widely blamed on

    global warming.

    Warming Disaster (Top) A satelliteimage of the Wilkins Ice Shelf, taken onApril 27, shows icebergs covering anarea of 700 sq km that have broken off.

    Professor Angelika Humbert, a

    glaciologist of the University of

    Muenster (Germany) analysed theEuropean Space Agency Satellite

    images of the Shelf of Antarctic and

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    C.S.V. / July / 2009 / 538

    came to this conclusion. She (Prof.

    Humbert) said about 700 sq km of

    ice–bigger than Singapore or Bahrainand almost of the size of New York

    City–broke off the Wilkins and

    shattered into a mass of icebergs.

    She said 370 sq km of the ice

    had cracked in recent days from the

    Shelf, the latest of about 10 shelves

    on the Antarctic Peninsula to retreatin a trend linked by the U.N. Climate

    Panel to global warming.

    The new icebergs added to 330

    sq km of ice that broke up earlier in

    April 2009 with the shattering of an ice

    bridge apparently pinning the Wilkins

    in place between Charkot island and

    the Antarctic Peninsula.

    Nine other ice shelves have

    receded or collapsed around the

    Antarctic Peninsula during the past 50years, often abruptly like the Larsen A

    in 1995 or the Larsen B in 2002. The

    trend is widely blamed on climate

    change caused by heat-trapping

    gases from burning fossil fuels.

    Most Distant Object inthe Universe Spotted

    Astronomers have spotted the

    most distant object in the universe,

    which is self-destructing star that

    exploded 13·1 billlion light years from

    Earth. It detonated just 640 million

    years after the big bang, around the

    end of the cosmic ‘dark ages’, when

    the first stars and galaxies were

    lighting up space. The object is a

    gamma-ray burst—the brightest type

    of stellar explosion. Gamma-rays

    bursts occur when massive spinning

    stars collapse to form black holes and

    spew out jets of gas at nearly the

    speed of light.

    Stars ‘Eat Up’ Planets

    Cannibalism is rampant in our

    universe. Stars ‘eat’ the exoplanetsthat venture near them. The new

    study has revealed that the

    exoplanets are doomed to prematuredeaths even before they could get

    close to be ripped apart by the host

    star’s gravity, a finding that may helpexplain why few exoplanets are found

    next to host stars. The research team

    is lead by Professor Brian Jackson of

    the University of Arizona (U.S.A.).

    In accordance with this research,

    a star’s gravity can put a nearby

    planet on a ‘fast track’ to spirallinginto the star and may also cause the

    planet to lose much of its atmosphere.

    More than 300 exoplanets have

    been catalogued to date. Many are

    situated close to the host stars. Butthe closestin ones are commonly

    found some 0·05 astronomical units

    (AU) from their host stars. But, no

    one is sure why the planets seem to

    pile up there. Very close to a star, at

    a boundary called the Roche limit,

    planets are dismembered by the

    star’s gravity. But the migration of

    planets seems to stop there ? Some

    models suggest gas and dust in the

    disc around a star could drag theplanets inward.

    Forthcoming SpaceTelescopes to Peek into

    Future

    A couple of space telescopes,

    that are going to be launched very

    shortly, will answer some of the

    biggest questions of the universe.

    Scientists hope that the probes will

    answer questions such as how did we

    get to, where we are now, and where

    are we likely to end up.

    Each telescope is designed to

    probe the deepest reaches of space

    to unravel the origins of matter, from

    the earliest beginnings of the

    universe, some 13·7 billion years ago

    to the creation of the stars, galaxies

    and planets. One of the telescopes

    called, ‘Planck’, will study in

    unprecedented detail of the ancient

    ‘fossilized’ radiation left over as a relic

    of the big bang. The analysis could

    help to explain how the universe

    formed through a process of rapid

    expansion in the first fractions of a

    second after the big bang itself.

    The other space telescope to be

    launched is ‘Herschel’. It will concen-

    trate on the invisible, infrared radiation

    emitted by the star-forming regions of

    the galaxies on the hope of explaininghow stellar objects from stars like the

    Sun to planets such as Earth, can

    form from clouds of cosmic gas, dust

    and debris. Scientists involved in thetwin missions hope that the data

    gleaned from instruments on board

    each space telescope will enablethem to fill in the remaining mysteries

    of how the universe came into exis-

    tence, how it evolved and how it is

    likely to end—if indeed it ever will.

    Flowers May Bloom onJupiter’s Icy Moon

    Scientists have suggested that

    spacecraft should hunt for signs of life

    on Jupiter’s ice-covered moon,

    Europa, since it would be detectable

    there in the form of blooming flowers.

    Life could be visible from orbiting

    spacecraft, however, if it made a hole

    in cracks in Europa’s shell that con-

    nect the surface to the interior,physicist and futurist, Professor

    Freeman Dyson reported. Such life

    might take the form of flowers that

    focus sunlight on the interior of the

    plant.

    Europa flowers could be detect-

    able through retro-reflection, an

    optical effect that is seen in light

    reflected from animals’ eyes.

    ●●●

    UPKAR PRAKASHAN, AGRA-2E-mail : [email protected] Website : www.upkar.in

    (Useful for Various Competitive Exams.)Useful for Various Competitive Exams.)

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    Wajed Mia—Nuclear scientist

    and Bangladesh Prime Minister

    Sheikh Hasina’s husband, Wajed Mia

    (66), died of prolonged illness and

    multiple complications in Dhaka on

    May 9, 2009.

    General Elections 2009—India

    voted decisively for continuity and

    stability in the general election to the

    15th Lok Sabha, giving the Congress-

    led United Progressive Alliance

    (UPA) another five-year term in office.

    People of India spoke and spoke with

    great clarity. In contrast to 2004, the

    UPA won close to 260 of the total 543

    seats did not need the support of Left

    Parties. The allies of Congress are—

    Nationalist Congress Party, the All

    India Trinamool Congress, theDravida Munnetra Kazhagam, the

    National Conference, and the All

    India Majlis-e-Ittehadul Muslimeen.

    Now, Manmohan Singh is the first

    Prime Minister since Indira Gandhi to

    have two full terms.

    Parties and their Vote Share

    Party

    Total

    seats

    Change

    from

    2004

    Vote

    share

    (%)

    Congress 206 61 29·67

    BJP 116 – 22 19·29

    JD (U) 20 12 1·58

    CPM 16 – 27 5·52

    CPI 4 – 6 1·46

    BSP 21 2 6·27

    AIADMK 9 9 1·79

    DMK 18 2 1·91

    TC 19 17 3·43

    NCP 9 0 2·24

    SP 23 – 13 3·44

    TDP 6 1 1·53

    SS 11 – 1 1·67

    RLD 5 2 0·49

    SAD 4 – 4 0·92

    NC 3 1 0·13

    RJD 4 – 20 1·31

    LJP 0 – 4 0·48

    TRS 2 – 3 0·63

    BJD 14 3 1·35

    AGP 1 – 1 0·45

    INLD 0 0 0·33

    JD(S) 3 0 0·89

    JMM 2 – 3 0·43IUML 2 1 0·23

    IND 9 2 4·16

    Others 16 – 9 8·4

    The triumph of the Congress was

    actually an aggregation of specific

    successes across different states.

    The party retained its base in Andhra

    Pradesh, cut its losses in Madhya

    Pradesh, recovered lost ground in

    West Bengal, Keral and Rajasthanand combined well with its allies in

    Maharashtra and Tamil Nadu.

    The BJP and Left parties are the

    big losers in the current general

    election.

    Ashok Chawla (New Finance 

    Secretary )—Economic Affairs Secre-

    tary, Ashok Chawla, took over as the

    Union Finance Secretary, succeedingArun Ramanathan who retired. Mr.

    Chawla is an IAS officer of 1973

    batch of Gujarat cadre.

    P. K. Barbora (New Vice Chief 

    of Air Staff )—Air Marshal P. K.

    Barbora has been appointed as the

    new Vice Chief of Air Staff. He will

    assume the charge on June 1, 2009.

    Currently, he has been serving as the

    Air Officer Commanding-in-Chief of

    Western Air Command.

    Deepak Verma  (New Judge,Supreme Court )—Justice Deepak

    Verma (61), Chief Justice of Rajas-

    than, has been appointed as the

    Judge of Supreme Court. He hails

    from Madhya Pradesh and will have a

    tenure of about four years.

    Balbir Singh Chauhan (New 

    Judge, Appex Court )—President

    Pratibha Patil cleared the appointment

    of Justice Balbir Singh, Chief Justiceof Orissa High Court, as the judge of

    the Supreme Court.

    Naveen Patnaik (CM, Orissa )—Biju Janta Dal President NaveenPatnaik was sworn-in as ChiefMinister of Orissa for the third conse-cutive term. Twenty other legislatorswere also sworn-in as the Ministers.Patnaik’s Party won 103 seats in the147 member Assembly.

    Pawan Chamling (CM, Sikkim )—Pawan Chamling was sworn-in as

    Chief Minister of Sikkim for a fourthsuccessive term, making him thelongest serving Chief Minister in thestate. Eleven other Ministers werealso sworn-in. Chamling’s SikkimDemocratic Front created history bywinning in all 32 Assembly seats.

    D. D. Lapang (CM, Meghalaya )—A seven member Congress andUnited Democratic Party coalitionMinistry, headed by D. D. Lapang,was sworn-in at the Raj BhavanShillong.

    Zuma (New President, S.A.)—Jacob Zuma, the indefatigable fighteragainst apartheid was sworn-in asliberated South Africa’s fourth Presi-dent.

  • 8/15/2019 52313794 Competition Science Vision July09

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    Dr. Manmohan Singh—Presi-

    dent Pratibha Patil administered the

    oath of office and secrecy to Dr.

    Manmohan Singh as the Prime

    Minister of India alongwith his cabinet

    colleagues in Rashtrapati Bhavan on

    May 22, 2009. This is Dr. Singh’ssecond successive term.

    President Pratibha Patil is administer-ing the oath of Office and Secrecy toDr. Singh

    Prime Minister Manmohan Singh

    was born on September 26, 1932, in

    a village in the Punjab province of

    undivided India. Dr. Singh completed

    his Matriculation examinations from

    the Punjab University in 1948. His

    acadmic career took him from Punjab

    to the University of Cambridge, UK,

    where he earned a First Class

    Honours degree in Economics in

    1957. Dr. Singh followed this with a

    D. Phil in Economics from Nuffield

    College at Oxford University in 1962.

    His book, ‘‘India’s Export Trends and

    Prospects for Self-Sustained Growth’’

    [Clarendon Press, Oxford, 1964] was

    an early critique of India’s inward-

    oriented trade policy.

    In 1971, Dr. Singh joined the

    Government of India as Economic

    Advisor in the Commerce Ministry.

    This was soon followed by his

    appointment as Chief Economic

    Advisor in the Ministry of Finance in

    1972. Among the many Governmental

    positions that Dr. Singh has occupied

    are Secretary in the Ministry of

    Finance; Deputy Chairman of the

    Planning Commission; Governor of

    the Reserve Bank of India; Advisor of

    the Prime Minister; and Chairman of

    the University Grants Commission.

    In what was to become the

    turning point in the economic history

    of independent India, Dr. Singh spentfive years between 1991 and 1996 as

    India’s Finance Minister. His role in

    ushering in a comprehensive policy of

    economic reforms is now recognized

    worldwide. In the popular view of

    those years in India, that period is

    inextricably associated with Dr.

    Singh.

    Among the many awards and

    honours conferred upon Dr. Singh in

    his public career, the most prominent

    are India’s second highest civilian

    honour, the Padma Vibhushan (1987);

    the Jawaharlal Nehru Birth Centenary

    Award of the Indian Science Congress

    (1995); the Asia Money Award for

    Finance Minister of the Year (1993

    and 1994); the Euro Money Award for

    Finance Minister of the Year (1993),

    the Adam Smith Prize of the Univer-

    sity of Cambridge (1956), and the

    Wright’s Prize for Distinguished

    Performance at St. John’s College in

    Cambridge (1955). Dr. Singh has also

    been honoured by a number of otherassociations including the Japanese

    Nihon Keizai Shimbun.

    Dr. Singh and his wife Mrs.

    Gursharan Kaur have three daugh-

    ters.

    During the last 26 years, LTTE

    rewrote many of the standards of

    terrorism. The Sri Lankan armed

    forces won a comprehensive victory

    over the LTTE in a military campaign

    that began in the eastern province in

    August 2006. With its entire top

    leadership and thousands of fighting

    cadres are killed in action, its military

    structure, assets and capabilities are

    destroyed, its political organization

    decimated, the LTTE no longer exists.

    Belying conventional wisdom, Sri

    Lanka has found a military solution to

    what used to be regarded as an

    intractable armed secessionist andterrorist challenge. Over a quarter of

    century, this war waged and claimed

    tens of thousands of lives.

    The images of terrified children,

    women and men fleeing the tiny sliver

    of coastal land in which they were

    confined by the Tigers for use as

    human shieled. Senior LTTE leaders

    made a final hopeless stand for a lost

    cause will continue to haunt the

    memories of journalists and others

    who witnessed these scenes.As the years went by and

    numerous proposals for a negotiated

    political solution fell by wayside, the

    one thing that remained constant was

    the LTTE’s uncompromising seces-

    sionism and militarism, and the rising

    graph of its terrorist crimes, which

    included the assassination of the

    former Indian Prime Minister, Rajiv

    Gandhi, Sri Lankan President

    Premdasa, a Sri Lankan Defence

    Minister, a Foreign Minister and

    countless others.

    Now, in the post Prabhakaran

    era, the Sri Lankan Government

    needs to address two big tasks—

    rehabilitation of hundreds of thou-

    sands of Tamils who have been

    through a prolonged nightmare and

    crafting an enduring political solution

    based on far-going devolution of

    power to the Tamils in their areas of

    historical habitation. India, which has

    excellent relations with its southern

    neighbour, can make a constructive

    difference by coming up with a

    massive rehabilitation package for the

    North and encouraging Colombo to

    fast-track the political solution.

    SPORTS

    Cricket

    IPL-2—The final of Indian

    Premier League cricket match wasplayed in Johannesburg between

    Deccan Chargers and Royal Challen-

    gers, Bangalore on May 24, 2009 at

    the Wanderers. Anil Kumble was the

    ‘Captain of Royal Challengers,

    Bangalore’ while Adam Gilchrist was

    the Captain of Deccan Chargers. A

    fighting unbeaten half century by

    Herschelle Gibbs (53 runs not out)

    took Deccan Chargers 143 for six

    wicket.

    But then it appeared initially to bean innings dominated by a bowler, leg

    spinner Anil Kumble, who finished four

    wicket for sixteen runs. Three of his

    scalps were—Adam Gilchrist, A.

    Symonds and Rohit Sharma. In a

    brilliant play, Kumble picked himself

    to bowl the first over after inviting

    Chargers to bat. It was Captain versus

    Captain when Kumble operated to the

    in-form.

    Finally, the Royal Challengers,

    Bangalore could score only 137 runsfor 9 wickets and lost to Deccan

    Chargers by six runs.

    ●●●

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    Physics

    1. What is the relation between v , ω  and r  (in vectorform) ?

    ➠ →→→→v  =

    →→→→ωωωω  ×××× 

    →→→→r 

    2. What does the plug marked infinity in a resistance

    box have below it ?

    ➠only air gap

    3. What is the moment of inertia for elliptical lamina ?

    ➠ I = (1/4) Ma  2 (about minor axis)

    and I = (1/4) Mb  2 (about major axis)

    4. How many protons and neutrons does anα

    -particle

    possess ?➠Two protons and two neutrons

    5. What is tractive force ?➠ F = (P/ v )

    6. What is conserved in the case of a freely falling

    body ?➠sum of kinetic and potential energies

    7. What is the pressure-temperature law ?➠ (P1 /T1) = (P2 /T2)

    8. An astronomical telescope is made of two lenses of

    powers 5 D and 20 D. Its magnifying power for nor-

    mal vision is

    ➠4

    9. What is Poynting vector ?

    ➠ →→→→ S =

    →→→→ E ×××× 

    →→→→ H =

    1

    µµµµ0  (→→→→ E ×××× 

    →→→→ B) = c  2 εεεε0 (

    →→→→ E ×××× 

    →→→→ B)

    10. To which region does the electromagnetic radiation of

    wavelength of the order of 1°A belong ?

    ➠  X-ray radiation

    11. What is ratio of the reflected intensity and incident

    intensity ?

    ➠ 

    Ir 

    Ii  = ( )n  1 – n  2

    n  1 + n  2 

    2

    12. A 4 µF condenser is charged to 400 volt and then itsplates are joined through a resistance. Heat produced

    in the resistance is

    ➠ 0·32 joule

    13. What is polarization vector ?

    ➠ (i) →→→→P  =

    QPA

    , (ii) →→→→P  = εεεε0 χχχχ Ed 

    14. How will you connect three capacitors of 3 µF each

    so that the capacitance of the combination is 4·5 µF?

    ➠  Two in series and then one in their parallel15. What is the trajectory of a charged particle when it is

    projected perpendicular to a magnetic field ?

    ➠ Circle in a plane perpendicular to the field

    16. When a radioactive nucleus emits a β-particle, theneutron to proton ratio

    decreases17. What is the dimensional formula of Hubble’s constant

    is

    ➠ [M0 L0 T –1]

    18. In nuclear reactor what is the function of moderators ?

    ➠To slow down fast fission neutrons

    19. What will be the force when dipoles are along the line

     joining their centres ?

    ➠ µµµµ04ππππ ·

    6M1 M2r 4

     (along r )

    20. What provides the centripetal force to enable an earth

    satellite to move in a circular orbital ?➠The gravitational force of attraction between the

    earth and the satellite

    Chemistry

    21. The esters of long chain fatty acids with long chain

    alcohols are commercially known as

    ➠ Waxes

    22. The lines in the spectrum of hydrogen atom in the

    visible region are termed as➠Balmer series

    23. Both mass and volume are extensive properties but

    the ratio of mass of a sample to its volume is an

    intensive property, known as

    ➠ Density

    24. The idea of elliptical orbits was propounded by

    ➠Sommerfeld

    25. The scientist who first pointed out that an element is

    any substance that cannot be decomposed into a

    simpler substance

    ➠ Robert Boyle’s

    26. Certain materials like potassium emit electrons when

    irradiated with visible light. This is known as

    ➠Photoelectric effect

    27. The term isotope was introduced by

    ➠ Frederick Soddy

    28. High lattice energy of an ionic compound is favoured

    by

    ➠Small inter-ionic distance and high

    charge on ions

    29. 1 mol of O is equal to 16·0 gm and 1 mol of O2 will be

    equal to

    ➠ 32·0 gm30. The chemical compounds which exist over a range of

    chemical composition are known as

    ➠Berthollide compounds

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    31. When neutron is outside the nucleus, it is unstable

    and it changes into a proton, and electron and ano-

    ther elementry particle, known as

    ➠ Neutrino

    32. The product of the net positive or negative charge

    and distance between the two charged ends is known

    as

    ➠Dipole-moment

    33. When a neutron collides with a proton, a nucleus of➠ Deuterium is formed

    34. Who discovered chlorine ?

    ➠C. W. Scheele (1774)

    35. A cold glow given out by some substances is called

    ➠ Phosphorescence

    36. Entire mountain ranges in Italy consist of mineral

    dolomite. Chemically dolomite is

    ➠MgCO3·CaCO3

    37. The crystals that can detect ultrasound and produce

    ultrasound are known as

    ➠ Piezoelectric crystals

    38. Fluoroapatite is commercially important as a source

    of phosphate. The composition of fluoroapatite is

    ➠ [3{Ca3(PO4)2}·CaF2]

    39. The SI unit of pressure is

    ➠ Pascal (Pa) [1 atm = 101,325 Pa = 101·325 kPa]

    40. Aluminium articles are often given decorative finishby electrolysing dil. H2SO4 with the aluminium anode.

    This process is known as

    ➠Anodising

    Zoology

    41. What is the name of the hormone that causes deposi-

    tion of fat in breast and hips in female humans during

    puberty ?

    ➠ Estrogen

    42. A group of coelomate metazoans in which the first

    embryonic opening is associated with the mouth is

    ➠Protostome

    43. Which ion must be present for binding of the cross

    bridges in muscles ?➠ Calcium

    44. Most of the carbon dioxide is transported in the blood

    stream of humans is

    ➠Bicarbonate ion

    45. What is called the form of enzymes that are encoded

    by different allelic genes ?

    ➠ Allozymes

    46. A small calcareous granules found in the inner ear of

    many mammals, is

    ➠Otolith

    47. Over production of which neurotransmitter has beenassociated with the mental disorder, called

    schizophrenia ?

    ➠ Dopamine

    48. Ridges or folds found in the lining of vertebrate

    stomach is called

    ➠Rugae

    49. Where each restriction enzyme cleaves a molecule ?

    ➠ At a particular nucleotide sequence

    50. A rod of bone or cartilage that forms the only ear

    ossicle in amphibians, birds and reptiles is called

    ➠Collumelar auris

    51. Where the spermatogenesis occurs ?

    ➠ Seminiferous tubules

    52. In cerebrum, the roof of each paracoel is called

    ➠Pallium

    53. Which hormone prevents dehydration of human

    body ?

    ➠ ADH

    54. Part of coelom in mammals containing lungs and

    lined by pleura is

    ➠Viscera

    55. Which area of human brain is responsible for arousaland wakefulness ?

    ➠ Reticular formation

    56. Large marine mammals well adapted for aquatic life

    are collectively known as

    ➠Cetacea

    57. Which ion is most concentrated outside a resting

    potential ?

    ➠ Sodium

    58. The endocrine part of pancreas consists of

    ➠ Islets of Langerhans

    59. Which kind of cells transmit the sensory impulses inhuman eye to optic nerve ?

    ➠ Ganglion cells

    60. The cells from Graafian follicle that surround the ovu-

    lated mammalian egg are known as

    ➠Cumulus cells

    Botany

    61. Who prepared an infectious extract from tobacco

    plants that were suffering from mosaic disease ?➠ D. I. Ivanovsky

    62. When does chromosome number becomes halved ?

    ➠ In meiosis during anaphase-I

    63. What type of lysine, an amino acid, is ?

    ➠ Basic amino acid

    64. What food is used by fungal partner made by algal

    partner in a lichen ?

    ➠Mannitol

    65. What refers to the number of death per unit time ?

    ➠ Mortality

    66. What is the major role of phosphorus in plantmetabolism ?

    ➠To generate metabolic energy

    (Continued on Page 612 )

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    ThermodynamicsThermodynamics is that branch of physics in which

    heat is converted into other forms of energy and other

    forms of energy are converted into heat. This branch

    deals the transformation of heat into mechanical work and

    the inter-relationship between them.

    Thermodynamical Variables

    Thermodynamical variables are those parameters

    which define the thermodynamical system completely.

    These are pressure (P), volume (V), temperature (T),

    internal energy (U) and entropy (S). These are also called

    thermodynamical coordinates.

    Thermodynamical Equilibrium

    A system is said to be in thermodynamical equili-

    brium if the temperature of its various parts is the same

    and equal to that of surroundings.

    External Work done (W)

    When a body is heated, it expands. This is opposed

    by external atmospheric pressure. The work done against

    external atmospheric pressure during expansion of a body

    is called external work.

    ∴ Work done = Force × displacement

    = Pressure × area × displacement

    = Pressure ×  change in volume

    or∆W = P ∆V

    ∆W = P (V2 – V1)

    where,

    V1 = Initial volume of gas, V2 = Final volume of gas

    (i) If V2 > V1, then ∆W = +ve, then work is done by

    the system(ii) If V2 < V1, then ∆W = –ve, then work is done on

    the system

    (iii) If V1 = V2  or V = constant, then ∆W = 0

    ● If pressure is constant, then work done

    W = P(V2 – V1)

    ● If pressure and volume both are variable then the

    work done

     W = ∫ V1

    V2P d  V

      = Area between P -V curve and volume axis

    ● If the system expands into vacuum (free expansion),

    then

    ∆W = 0

    P-V diagram or indicator diagram—A graph bet-ween pressure (P) and volume (V) is known as P-V

    diagram or indicator diagram.

    Area under P-V diagram = Work done.

    Area = Work done by thegas in path AB

    A

    P

    V

    B

    Cyclic Process (or Closed Path)

    Cyclic process is that process in which the system

    returns to its original state (P, V, T) after doing work or

    after work being done on it.

    The work done on the system or work done by the

    system depends upon the area of cycle. If the cycle traced

    in clockwise direction then the network is done by the gas

    and if the cycle is traced in anticlockwise direction the network is done on the gas.

    Conversion of units—Work is measured in joule or

    erg and heat is measured in kilo calorie or calorie. In the

    relation W = JH, J is conversion factor.

    In C.G.S. system J = 4·2 × 107 erg/cal

    In M.K.S. system J = 4·2 × 103 joule/k cal

    = 4·2 joule/cal

    In F.P.S. system

    J = 778 foot-pound/B.Th.u.

    Example 1. When a body falls from a great height

    (e.g., water in a waterfall), potential energy is finally

    converted into heat energy. Here the temperature

    increases slightly.

    mgh  = J × ms ∆t 

    ∴ ∆t   =gh 

    Js 

    Example 2. When a bullet is fired at a target, kinetic

    energy is converted into heat energy and the temperature

    increases too much.

      HereIf bullet does not melt

    and

    If bullet melts

     1

    2 mv 2 = J (ms  ∆t )

    1

    2 mv 2 = J (ms  ∆t  + m  L)

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    (d) For isobaric change—In this process

    P = Constant.

    Q =   m  Cp  ∆t 

    ∆U =   m  Cv  ∆t 

    Here, Cp is specific heat of gas at constant pressure.

    Therefore, in isobaric change the heat supplied to the

    system is used partly in changing the volume and partly in

    changing temperature.

    (e) For isolated system—An isolated system is one

    which is completely cut off from the surroundings,

    therefore, Q = 0, and there is no change in internal energy

    i.e., ∆U = 0 and hence, ∆W = 0. So system does not

    perform any work.

    (f) For cyclic process—For this process change in

    internal energy ∆U = 0.

    Hence, Q = W

    i.e., whole of the heat supplied to the system is used

    in doing work against external pressure.

    Specific Heat of GasesSpecific heat of a gas depends on the condition of

    pressure and volume of the gas during its heating.

    Accordingly specific heat of a gas may be anything from

    zero to infinity.

    In general two modes of heating a gas has been

    selected. They are (a) At constant pressure (b) At cons-

    tant volume.

    Accordingly there are two specific heats in case of

    gases.

    (i) Specific heat at constant pressure (Cp )

    (ii) Specific heat at constant volume (Cv )

    Cp  > Cv —In case of Cv , volume V = Constant

    ⇒ ∆V = 0

    Hence, work done by gas W = P ∆V = 0 but in case of

    Cp , pressure P = constant. Therefore, when gas is heated

    its volume increases and some work (W = P ∆V) is done

    by the gas. Hence extra amount of heat should be givento the gas to do this work. So Cp  > Cv .

    Cp  – Cv  = Extra work done

    = P ∆V

    = PV2 – PV1= RT2 – RT1

    = R (T + 1) – RT

    = R

    ∴ Cp  – Cv   = R

    It is known as Mayer’s formula

    For one gm mole gas

    Cp  – Cv   ~  –  2 cal/mole-K

    Molar Specific Heat

    It is equal to specific heat multiplied by the molecular

    weight M.

    Thus, Cp  = M × Cp 

    and Cv  = M × Cv 

    Values of Specific Heats Cp  and Cv   for Gases

    (a) For monoatomic gases (e.g., He, Ne, Ar etc.)

    Cv  =3

    2 R ~  – 3 cal/mole-K

    Cp  =5

    2 R ~  – 5 cal/mole-K

    γ =Cp C

      = 1·67

    (b) Diatomic gases (e. g., H2, O2, N2 etc.)

    Cv  =5

    2 R

    ≈ 5 cal/mol-K

    Cp  =7

    2 R

    = 7 cal/mole-K

    γ =Cp Cv 

      = 1·4

    (c) Polyatomic gases

    Cv  = 3 R = 6 cal/mole-KCp  = 4R ~   – 8 cal/mole-K

    γ =Cp Cv 

     = 1·33

    ● For n moles of gas

    ∆U =   n  Cv  ∆T

    and   ∆Q =   n  Cp  ∆T

    ∴ ∆W =   ∆Q – ∆U = n  R ∆T

    Nature of Internal Energy

    Every thermodynamic system has some internal

    energy which is characteristic of its state. It consists of

    kinetic energy due to molecular motion and potential

    energy due to molecular attraction.

    We know that monoatomic molecules undergo only

    translational motion, i.e., the centre of mass of the mole-

    cule moves [fig. (a)]. Hence, these molecules have kinetic

    energy due to translational motion.

    Translational Motion(a)

    Rotational Motion(b)

    Vibrational Motion

    (c)

    Diatomic and polyatomic molecules undergo not only

    the translational motion inside the substance; but also

    rotate about the axis passing through the centre of massof the molecule [fig. (b)] and also vibrate relative to each

    other [fig. (c)]. Thus, in diatomic and polyatomic molecules,

    in addition to translational motion, there is also internal

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    rotational motion and vibrational motion. Hence, these

    molecules in addition to translational kinetic energy, have

    rotational kinetic energy and vibrational kinetic energy

    also.

    Thus, the internal energy of a substance consists of :

    (i) The translational kinetic energy of molecules.

    (ii) The internal rotational and vibrational kinetic

    energies of molecules (if they are polyatomic).

    (iii) The potential energy of the molecules due tointer-atomic forces.

    Important Points to Note

    1. Ideal gases—In case of ideal gases there is no

    molecular attraction between the molecules. Hence, they

    have no potential energy. Thus, the internal energy of an

    ideal gas is only the kinetic energy of its molecules.

    2. Real gases—In real compressed gases the

    molecules come closer and so exert appreciable force on

    one another. Hence, potential energy also adds to their

    internal energy. Since, potential energy is negative, it

    follows that internal energy of a compressed gas is less

    than its internal energy in rarefied state at the same

    temperature.

    3. Liquids—Molecules in liquids are very close to

    one another exert stronger forces and possess sufficient

    potential energy. But their translation motion is very

    limited in comparison to gas molecules. Since potential

    energy is negative, the internal energy of the liquids is

    very small compared to the internal energy of the gas at

    the same temperature.

    4. Solids—In solids molecules are fixed in definite

    positions in a lattice. These molecules vibrate to and fro

    about these positions but can not leave these positionspermanently. These vibrations are called lattice vibrations.

    In solids the potential energy of molecules is very large.

    Since this is negative, the internal energy of solids is less

    than that of liquids.

    5. Translational K. E. of molecules—According to

    the kinetic theory, the translational kinetic energy of the

    molecules (and not the whole internal energy of the

    substance) is directly proportional to the absolute

    temperature of the substance. Hence the temperature of

    the substance rises on increasing the translational kinetic

    energy of its molecules.

    Second Law of ThermodynamicsThe first law of thermodynamics states the equi-

    valence heat and mechanical work when one is

    completely converted into the other. It simply tells that

    when ever work is obtained an equivalent amount of heat

    is used up, or vice-versa . It does not say anything either

    about the limitation in the conversion of heat into work or

    about the condition necessary for such a conversion.

    The quest for deciding these points led to the

    formulation of Second Law of Thermodynamics. This

    law is generalisation of certain experiences and

    observations and is concerned with the direction in which

    energy transfers take place. This law has been stated invarious forms but all the statements are equivalent. Below

    are given two simple forms of this law. According to one

    statement :

    ‘It is impossible to convert ‘all’ the heat extracted

    from a hot body into work’

    According to a second statement :

    ‘It is impossible to transfer heat from a cold body

    to a hot body without expenditure of work by an

    external agency’.

    As an illustration we take the case of a heat engine.Here the working substance takes heat Q1 from the hot

    body (source), converts a part of it

    into work W and gives the rest Q2

    to a cold body (sink)

    No engine has ever been

    designed which may convert ‘all’

    the heat Q taken from the source

    into work W without giving any

    heat to the sink. For obtaining

    continuous work a sink is

    necessary. In other words, all the

    heat taken from a body cannot be

    converted into work.

     →W

    Hot Body(Source)

    Cold Body(Sink)

    Q 2

    Q 1

    ● A refrigerator is a heat engine running in the reverse

    direction. In it, the working substance (a gas) takes

    in heat from a cold body and gives out to the hotter

    body (external atmosphere). For doing this it uses

    electrical energy. No refrigerator has yet been

    designed which may transfer heat from a cold body to

    a hot body without using an external source of

    energy. It implies that it is impossible for a self-acting

    machine, unaided by any external agency, to transfer

    heat from a cold body to a hot body.

    Efficiency of Heat Engine

    η =Amount of heat converted into mechanical work

    Amount of heat taken from the source

    =Q1 – Q2

    Q1

    = 1 –Q2Q1

    Carnot engine (Reversible cycle)

    For a reversible cycle

    Q1Q2

    =T1T2

    ∴ η = 1 –T2T1

     Refrigerator

    ← Mechanical

    work

    Q1

    Q 2 

    W = Q1 – Q2

    Hot BodyT K1

    Cold BodyT K2

    The efficiency of rever-sible thermodynamic cycle(Carnot cycle) depends not onthe nature of the gas, but onlyon the temperature rangebetween which it operates.

    Carnot’s theorem—Noengine can be more efficientthan a reversible engineworking between the sametemperatures.

    W = Amount of mechani-cal work given from outsidewhich changes into amount(Q1 – Q2) of heat.

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    At a Glance

    Efficiency of Engines

    Steam engine—ηs   = 17% (Max.)

    Petrol engine—ηp   = 44% (Max.)

    Diesel engine—ηd   = 55% (Max.)

    Thus,   ηd  > ηp  > ηs 

    Electric engine

    η = 90% (Max.)

    The coefficient of performance of the refrigerator.

    β =Q2W

     =Q2

    Q1 – Q2

    For a reversible cycle

    Q1Q2

    =T1T2

    ∴  β =T2

    T1 – T2

    Relation between ββββ and ηηηη

    β =T2

    T1 – T2 =

    1

    T1T2

     – 1

    and   η = 1 –T2T1

    or

    T2T1 = 1 – η

    orT1T2

    =1

    1 – η

    ∴ β =1

    1

    1 – η – 1

    β =1 – η

    η

    OBJECTIVE QUESTIONS01. The volume of a gas expands by

    0·25 m3  at constant pressure of

    103  Nm –2. The work done is

    equal to—

    (A) 2·5 erg (B) 250 joule

    (C) 250 watt (D) 250 newton

    02. An ideal monoatomic gas is

    taken round the cycle ABCDA as

    shown in the P-V diagram. The

    work done during the cycle is—

    P

    (2P, V) (2P, 2V)

    A

    D

    (P, V) (P, 2V)

    B

    C

    V  →

    (A) PV (B) 2 PV

    (C)

    1

    2 PV (D) Zero

    03. 1 gm water at 100°C becomes

    1671 c.c. steam at 100°C and at

    1 atmosphere pressure when

    540 cal heat is supplied. The

    external work done is nearly—

    (A) 2268 J (B) Zero

    (C) 169 J (D) 2100 J

    04. If 10 moles of oxygen gas is

    heated at constant volume from

    20°C to 40°C. The change ininternal energy of the gas is—

    (A) 1400 cal (B) 1000 cal

    (C) 400 cal (D) 1000 kilo cal

    05. A bullet moving with a uniform

    velocity v   stops suddenly after

    hitting the target and the whole

    mass melts. If the mass of the

    bullet be m , specific heat S, initial

    temperature 25°C, melting point

    475°C and latent heat L. Then—

    (A) m L = m S (475 – 25) + 1/2

    mv 2/J

    (B) m S (475 – 25) + m L = 1/2

    mv 2/J

    (C) m S (475  – 25) + m L = 2J/ mv 2

    (D) m S (475  – 25) = m L + 2J/ mv 2

    06. A waterfall is 84 m high. Assum-

    ing that half of the kinetic energy

    of the falling water gets converted

    into heat, the rise in temperature

    of water is—

    (A) 0·098°C (B) 0·98°C

    (C) 9·8°C (D) 0·0098°C

    07. 1 gm coal gives 2 kilo cal of heateffectively on burning. The coal

    costs 14 paise per kg. The cost to

    produce 1 kWh electrical energy

    is—

    (A) 60 paise (B) 6 paise

    (C) 1 paisa (D) 100 paise

    08. During the adiabatic expansion

    of 2 mole of a gas, the internal

    energy of the gas is found to

    decrease by 2 joule. The work

    done during the process on thegas will be equal to—

    (A) 1 joule (B) – 1 joule

    (C) 2 joule (D) – 2 joule

    09. If the amount of heat given to a

    system be 35 joule and the

    amount of work done by the

    system be – 15 joule, then the

    change in the internal energy of

    the system is—

    (A) – 50 joule (B) 20 joule

    (C) 30 joule (D) 50 joule

    10. A gas expands from 50 litre

    volume to 250 litre at 105  N/m2

    atm pressure. Calculate the workdone by the gas—

    (A) 2 × 107 J (B) 2 × 104 J

    (C) 2 cal (D) Zero

    11. The kinetic energy of gas mole-

    cules will be half the value at

    room temperature (27°C), when

    temperature becomes—

    (A) 327°C (B) 123°C

    (C) – 123°C (D) – 27°C

    12. The average energy associated

    per molecule for a gas whose

    molecules have n   degrees of

    freedom is—

    (A)1

    2 nk  T (B)

    nk  T

    N

    (C)1

    2 nk  T

    N(D)

    3

    2 k  T

    13. The efficiency of Carnot engine

    working between the source atabsolute temperature T1 and sink

    at absolute temperature T2 is—

    (A) T2T1

    (B) 1 – T1T2

    (C) 1 –T2T1

    (D)T1T2

     – 1

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    14. A Carnot engine is working bet-

    ween temperature 527°C and

    27°C. Its efficiency will be—

    (A) 62·5% (B) 37·5%

    (C) 50% (D) 25%

    15. Theoretically the efficiency of

    Carnot engine is 100%, when the

    temperature of the sink is—

    (A) 0°C (B) 0K

    (C) 0°F (D) 0°R

    16. By opening the door of a refrige-

    rator which is inside the room—

    (A) The room can be cooled to a

    certain degree

    (B) Room can be cooled to the

    temperature of the refrige-

    rator

    (C) Ultimately room is slightlywarmed

    (D) The room is neither cooled

    or warmed

    17. One gram of ice, when melts,

    requires 336 joule of heat. The

    increase in internal energy will

    be—

    (A) Equal to 336 J

    (B) More than 336 J

    (C) Less than 336 J

    (D) Equal to zero

    18. A perfect gas is contained in a

    cylinder kept in vacuum. The

    cylinder suddenly bursts. The

    temperature of the gas—

    (A) Becomes 0 K

    (B) Remains unchanged

    (C) Becomes more than before

    (D) Becomes less than before

    19. A perfect gas is heated in anisothermal way. The heat will be

    used to—

    (A) Do external work

    (B) Increase temperature

    (C) Increase internal energy

    (D) Decrease internal energy

    20. In which process will the change

    in internal energy be equal to the

    work done ?

    (A) Isothermal process

    (B) Adiabatic process

    (C) Isochoric process

    (D) Isobaric process

    21. Work done in an adiabatic

    change for a perfect gas depends

    only on—

    (A) Change in volume

    (B) Change in pressure

    (C) Change in temperature

    (D) Change in heat content

    22. An ideal Carnot engine whoseefficiency is 40% receives heat at

    500 K, If the efficiency is to be

    50%, the intake temperature for

    the same exhaust temperature

    is—

    (A) 900 K (B) 800 K

    (C) 700 K (D) 600 K

    23. A given mass of a gas expands

    from the state A to the state B by

    three paths 1, 2 and 3 as shown

    in figure. If W1, W2  and W3respectively be the work done by

    the gas along the three paths

    then—

    AP

    3

    2

    1

    V

    B

     →

           →

    (A) W1 > W2 > W3(B) W1 < W2 < W3

    (C) W1 = W2 = W3

    (D) W1 < W2 and W1 > W3

    24. The specific heat of hydrogen

    gas at constant pressure is

    Cp  = 3·4 × 103 calorie/kg°C and

    at constant volume is Cv  =  2·4 ×

    103 calorie/kg°C. If one kilogram

    hydrogen gas is heated from

    10°C to 20°C at constant pres-

    sure the external work done on

    the gas to maintain it at constant

    pressure is—

    (A) 103 calorie

    (B) 5 × 103 calorie

    (C) 104 calorie

    (D) 105 calorie

    25. The differential form of first law of

    thermodynamics is—

    (A)   d  Q = d  U – d  W

    (B)   d  Q + d  U = d  W

    (C)   d  Q = d  U + d  W

    (D)   d  Q + d  U + d  W = 0

    26. Which of the following is not

    thermodynamic function ?

    (A) Enthalpy

    (B) Work done

    (C) Gibbs energy

    (D) Internal energy

    27. An ideal heat engine exhausting

    heat at 77°C is to have a 30%efficiency. It must take heat at—

    (A) 127°C (B) 327°C

    (C) 227°C (D) 673°C

    28. A Carnot’s engine first works

    between 200°C and 0°C and

    then between 0°C and – 200°C.

    The ratio of its efficiencies in

    these two cases is—

    (A) 1·000 (B) 0·722

    (C) 0·577 (D) 0·340

    29. In a Carnot’s engine, the tempe-

    rature of the source is found to

    be 727°C and that of sink to be

    27°C. The approximate effi-

    ciency of the engine is—

    (A) 0·7 (B) 0·9

    (C) 0·4 (D) 1

    30. A Carnot’s engine takes 300

    calorie of heat at 500 K and

    rejects 150 calorie of heat to the

    sink. The temperature of the sink

    is—

    (A) 1000 K (B) 750 K

    (C) 250 K (D) 125 K

    31. A lead bullet of mass 21 gm hits

    a hard target with a velocity 200

    m/s. The total amount of heat

    produced would be—

    (A) 100 cal (B) 1000 cal

    (C) 500 cal (D) 2000 cal

    32. A gas is compressed at a cons-tant pressure of 50 N/m2  from

    volume of 10 m3  to a volume of

    4 m3. Energy of 100 J is then

    added to the gas by heating. Its

    internal energy is—

    (A) Increased by 400 J

    (B) Increased by 200 J

    (C) Increased by 100 J

    (D) Decreased by 200 J

    33. In a thermodynamic process the

    pressure of a fixed mass of thegas is changed in such a manner

    that the gas releases 20 J of heat

    and 8 J of work is done on the

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    gas. If the initial energy of the

    gas was 30 J, then the final

    internal energy will be—

    (A) 2 J (B) 42 J

    (C) 18 J (D) 58 J

    34. Find the change in internal

    energy of the system when a

    system absorbs 2 kilo-calorie ofheat and at the same time does

    500 joule of work—

    (A) 7900 J (B) 8200 J

    (C) 5600 J (D) 6400 J

    35. The efficiency of a Carnot’s

    engine working between steam

    point and ice point is—

    (A) 16·8% (B) 26·81%

    (C) 36·8% (D) 46·8%

    36. The coefficient of performance ofa refrigerator working between

     – 10°C and 20°C is—

    (A) 8·77 (B) 6·77

    (C) 7·77 (D) 10·77

    37. From what minimum height a

    block of ice has to be dropped in

    order that it may melt completely

    on hitting the ground ? (L is the

    latent heat of ice and J is joules

    constant)

    (A)   mgh  (B)   mgh /J

    (C) JL/  g  (D) J/Lg 

    38. A Carnot’s engine takes in 3000

    k cal of heat from a reservoir at

    627°C and it gives it to a sink at

    27°C. The work done by the

    engine is—

    (A) 4·2 × 106 J

    (B) 8·4 × 106 J

    (C) 16·8 × 10

    6

     J(D) Zero

    39. An ideal heat engine workingbetween temperature T1  and T2

    has efficiency η. If both the tem-

    peratures are raised by 100 K

    each, the new efficiency of the

    heat engine will be—

    (A) Equal to η

    (B) Greater than η

    (C) Less than η(D) Greater or less than η   de-

    pending upon the nature of

    working substances

    40. A Carnot’s engine operates with

    a source at 500 k and sink at

    375 k. The engine takes in 600 k

    cal of heat in one cycle. The heat

    rejected to the sink per cycle is—

    (A) 250 k cal (B) 350 k cal

    (C) 480 k cal (D) 550 k cal

    41. The P-V diagram shows the

    thermodynamic behaviour of an

    ideal gas. The work done in the

    complete cycle ABCDA is—

    1

    A B

    D C

    2

    2

    4

    6

    8

    10

    12

    3 4 5 6

       P   (   1   0   5    N

       /  m   2   )

    V (litre)

    (A) 6000 J

    (B) 5000 J, done by the gas

    (C) 5000 J, done on the gas

    (D) 6 × 106 J done by the gas

    42. The figure shows the changes in

    a thermodynamical system as it

    goes from A → B →  C → A. It is

    given thatUA = 0, UB = 30 J and heat given

    to the system in the process

    B → C is 50 J.

    1

    BA

    ED

    C

    0

    30

    60

    90

    2 3

       P  r  e  s  s  u  r  e   P   (   N   /  m   2   )

    Volume V (m3)

    Which of the following inference

    from it is not correct ?

    (A) Internal energy of the system

    in state C is 80 J

    (B) Heat given to the system in

    process A →  B is 90 J

    (C) Heat taken out from the

    system in process C → A is – 200 J

    (D) Work done in complete cycle

    ABCA is 120 J

    ANSWERS WITH HINTS

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    Thermal RadiationHeat travelling by the process of radiation is called

    radiant heat or thermal radiation. When heat is propagated

    by radiation, no material medium is necessary for the

    transmission and if there is any medium it is not necessary

    that it should first get itself heated (as in case of conduc-

    tion and convection) before it could assist the propagation

    of thermal radiation. Thermal radiation has following pro-

    perties :

    (1) Thermal radiation travels through empty space with

    the velocity of light.

    (2) Thermal radiation exhibits properties of light. The only

    difference is that its average wavelength is greaterthan that of visible light. Therefore, the thermal radia-

    tion is called infrared radiation.

    At a Glance

    Some DefinitionsTotal energy density—The total energy density of radia-

    tions at any point is the total radiant energy per unit volumearound that point for all the wavelengths taken together. It isgenerally expressed by u , its unit is joule m – 3.

    Spectral energy density—The spectral energy densityfor a particular wavelength is the energy per unit volume perunit range of wavelength. This is denoted by u λ.

    Total emissive power—The total emissive power of abody is the radiant energy emitted per unit time per unit surfacearea of the body for all wavelengths taken together. It isdenoted by E.

    Spectral emissive power—The spectral emissive powerof a body at a particular wavelength is the radiant energyemitted per unit time per unit surface area of the body within aunit wavelength range. It is denoted by Eλ.

    Absorptive power—The absorptive power of a body at aparticular temperature and for a particular wavelength isdefined as the ratio of the radiant energy absorbed per unitsurface area per unit time to the total energy incident on thesame area of the body in unit time within a unit wavelengthrange. It is denoted by a λ.

    From these definitions

    u  =  ∫ ∞

    0

     u λd  λ  and E = ∫ ∞

    0

    Eλd  λ

    Black Body and Black Body Radiation

    A perfectly black-body is one which absorbs all the

    heat radiations, of whatever wavelength, incident on it. It

    neither reflects nor transmits any of the incident radiation

    and, therefore, appears black whatever be the colour of

    incident radiation.

    Let a black-body be placed in an isothermal enclosure.

    The body will emit the full radiation of the enclosure after it

    is in thermal equilibrium with the enclosure. These radia-tions are independent of the nature of the substance.

    Clearly the radiation from an isothermal enclosure is

    identical with that from a black-body at the same tem-

    perature. Hence, the heat-radiations in an isothermalenclosure are termed as black-body radiation.

    In practice no substance possesses strictly the pro-

    perties of a black-body. Lamp-black and the platinum black

    are the nearest approach to a black-body. However, the

    bodies showing close approximation to a perfectly black-

    body have been constructed e.g., Ferry’s black body and

    Wien’s black-body.

    Kirchhoff’s Law

    It states that the ratio of the emissive power to the

    absorptive power for a given wavelength at a given tem-

    perature is the same for all bodies and is equal to theemissive power of a perfectly black-body at that tempera-

    ture. Expressed in symbols, it is

    e λa λ

    = Eλ

    Pressure of Radiation

    The radiation possesses the properties of light. Like

    light it exerts a small but definite pressure on the surface

    on which it is incident.

    For normal incidence on the surface, the pressure of

    radiation is equal to the energy density, i.e.

    p  =   u  =I

    The density of radiation u   is simply the amount of

    radiation contained in unit volume and is, therefore, equal

    to I/ c   where I is the intensity of radiation and c  is the

    velocity of light.

    For diffuse radiation

    Pressure =1

    3 × Energy density

    p  =1

    3 u   =

    1

    I

    Stefan-Boltzmann LawStefan’s law states that the rate of emission of radiant

    energy by unit area of a perfectly black-body is directly

    proportional to the fourth power of its absolute tempera-

    ture. In symbols

    E =   σT4

    where σ is a constant and is called Stefan’s constant. The

    unit of σ is Jm – 2 s – 1K – 4 or Wm – 2 K – 4.

    The law in the above form refers to the emission only

    and not to the net loss of heat by the body after exchange

    with the surroundings. The law can be extended to repre-

    sent the net loss of heat and may be enunciated asfollows :

    A black-body at absolute temperature T surroundedby another black-body at absolute temperature T0 not only

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    loses an amount of energy σT4 but also gains σT04, thus,

    the amount of heat lost by the former per unit time is given

    by

    E = σ (T4 – T04)

    The law is known as Stefan-Boltzmann’s law as

    Boltzmann deduced it thermodynamically in 1884 and

    showed that the law strictly applies to emission from a

    perfectly black-body.

    Newton’s Law of Cooling

    It states that the rate of loss of heat from a body is

    proportional to the mean excess temperature of the body

    over the temperature of its surroundings provided that the

    temperature excess is small, i.e.

    Rate of loss heat from the body ∝ Mean temp. difference

    Consider a hot body of mass m , specific heat s  and at

    temperature θ1. Its temperature falls from θ1  to θ2 in a

    time-interval t , when the temperature of surroundings is θ0.

    Then

    Rate of loss of heat from the body =   ms  (θ1 – θ2)

    During cooling, average temperature of the body

    θ =θ1 + θ2

    2, so the average temperature-difference bet-

    ween the body and its surroundings is (θ – θ0). According

    to Newton’s law, we have

    ms  (θ1 – θ2)

    t   ∝ (θ – θ0)

    or   ms  

    (θ1 – θ2)

    t  =   k  (θ – θ0)

    where k  is a proportionality constant.

    Derivation of Newton’s Law from Stefan’s Law

    Consider that a hot body at temperature T is

    surrounded by a medium at temperature T′. According to

    Stefan’s law the net rate of loss of heat by the body is

    e   σ (T4 – T′4)

    where e  is emissive power of the body.

    Further suppose that temperature T of the body is

    only slightly  higher than the temperature T′  of its

    surroundings both at

    T – T′ =   ∆T

    or T = (T ′ + ∆T)

    so the rate of loss of heat is

    e  σ [(T′ + ∆T)4 – T′4] =   e  σ [ ]T′4 ( )1 + ∆TT′4 – T′4

    Since ∆T is very small compared to T ′, hence

    ( )1 + ∆TT′4

    = 1 + 4∆T

    T′

    by the binomial theorem neglecting higher powers of ∆T/T′

    ∴ Rate of loss of heat

    =   e  σ  [ ]T′4 ( )1 + 4∆TT′  – T′4

    =   e  σ (4T′3) ∆T

    ∝ ∆T

    The rate of cooling of a body depends upon the

    energy radiated by it. Hence, rate of cooling of a body is

    proportional to the mean temperature difference between

    the body and its surroundings.

    Thus, Newton’s law is only a special case of Stefan’s

    law for small temperature differences.

    Spectral Distribution of Black Body Radiation

    A perfectly black-body is a full radiator, i.e., it emits

    radiation of all possible wavelengths. Lummer and

    Pringsheim studied the spectral

    distribution of energy (i.e., energy

    distribution among different wave-

    lengths) in the radiation of a black

    body at different temperatures.

    Spectral distribution  curves so

    obtained are shown in the figure.

    T2

    T3

    T1

    λ

    T3 > T2 > T1

    These curves have the same general shape for all

    temperatures and give the following information regarding

    the characteristics of black body radiation :

    (i) At a given temperature T, with increase in wave-

    length λ, the energy Eλ  first increases, reaches a maxi-

    mum and then decreases. It means that for a given tem-

    perature, the radiant energy emitted by a black-body is

    maximum for a particular wavelength.

    (ii) As the temperature increases, the peak of the

    curve shifts towards shorter wavelength side, i.e., the

    maximum value of Eλ is obtained at smaller value of λ.Wien in 1896 established the following relation bet-

    ween temperature T and wavelength λm  corresponding to

    maximum emission.

     λm  T = constant = b  (suppose)

    This is called Wien’s displacement law.

    The constant b  is called Wien’s constant and has the value

    0·2896 cm K or 0·2896 × 10 – 2 mK

    (iii) As the temperature rises, the area enclosed by the

    curve goes on increasing. This area represents total energy

    E (for all wavelengths) emitted by a black body at that

    temperature. The areas enclosed by different curves, when

    measured, are found to be proportional to the fourth power

    of corresponding absolute temperatures. Thus

    E   ∝ T4

    This is Stefan’s law.

    (iv) Wien also proved that at a temperature T, themaximum emitted energy (Eλ)m   corresponding to wave-

    length λ  is proportional to the fifth power of that tempera-

    ture (T5). Thus

    (Eλ)m    ∝ T5

    This shows that on raising temperature, the maximum

    energy (Eλ)m   emitted corresponding to wavelength λ

    increases very rapidly.

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    SOME TYPICAL SOLVED EXAMPLES

    Example 1. A black-body radiates heat energy at a

    rate 1·45 ×××× 103  Js – 1 m – 2 at a temperature of 127°°°°C. At

    what temperature will it radiate heat at the rate of

    1·17 ×××× 105 Js – 1 m – 2 ?

    Solution :

    Example 2. At what temperature a perfectly black-

    body of area 104 m2 would radiate energy at the rate of

    90·72 Wm – 2 ? (Given : σσσσ = 5·67 ×××× 10 – 8 Wm – 2 K – 4)

    Solution

    Example 3. Estimate the temperatures at which a

    body would appear red and blue. The corresponding

    wavelengths of maximum emission are λλλλm  = 7500°°°°A

    and 5000 °°°°A respectively.

    (Given : Wien’s constant b  = 0·3 cm-K)

    Solution

    OBJECTIVE QUESTIONS

    1. A hot body will radiate heat most

    rapidly its surface is—

    (A) White and polished

    (B) White and rough

    (C) Black and polished

    (D) Black and rough2. The best black-body is—

    (A) A metal coated with a black

    dye

    (B) A lamp of charcoal heated to

    a high temperature

    (C) A glass surface coated with

    coal-tar

    (D) A hollow enclosure black-

    ened inside and having a

    small hole

    3. The colour of a star indicatesits—

    (A) Weight (B) Size

    (C) Distance (D) Temperature

    4. Three stars A, B and C appear

    green, red and blue respectively.

    The star having minimum tem-

    perature is—

    (A) A

    (B) B

    (C) C

    (D) All are at the same tempera-ture

    5. Two sphere A and B of the same

    material having radii 1m and 4m

    are at temperatures 4000 K and

    2000 K. Which will emit more

    energy per second ?

    (A) A

    (B) B

    (C) Equal for both(D) None of these

    6. Choose the wrong statement—

    (A) Black surface is a better

    absorber of radiation than a

    white one

    (B) Rou