Properties of Waves - Merit Tutors · 2018. 5. 25. · Properties of Waves Mark Scheme 2. Level...

Properties of Waves Mark Scheme 1

Level Edexcel

Subject Physics

Exam Board GCSE(9-1)

Topic Waves

Sub Topic Properties of Waves

Booklet Mark Scheme 1

53 minutes

/44

/100

Time Allowed:

Score:

Percentage:

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Question Number

Answer Acceptable answers Mark

1(a) A longitudinal : yes (1)

Question Number


1(b) An explanation linking any two of:

1. A cause or description ofearthquakes (1)

2. why timing of earthquakeis uncertain / complex (1)

3. we cannot see {what ishappening deep inside theEarth / where the platesare rubbing} (1)

The release of {energy / pressure/friction force} (in Earth’s surface)

(caused when tectonic) plates slide past each other

any idea of relative movement of plates e.g. move over each other, collide

(movement of plates is) {sudden / random / jerky}

it is too difficult to {work out / measure} when release of energy will happen

“it is difficult to measure when the plates will collide” = 2 marks

(2)


Question Number


1(c)

P-wave = 8 (minutes) (1)

S-wave = 14.5 (minutes) (1)

time difference = 6.5 (minutes) (1)

award full marks for correct answer (6.5) with no working (since 13 small squares = 6.5 mins)

7.5 – 8.5 (minutes) inclusive

14.0 - 15.0 (minutes) inclusive

ecf for difference of wrong readings from graph

accept time shown as m:ss (e.g. 6:30)

if correct construction lines are shown on graph but no values written, the score is maximum of 1 of the three

(3)


Question Number

Indicative Content Mark

QWC *1 (d)

A description including some of the following points

Data collection

S and P arrival times found Use or collect data from more than one station

Manipulation / Calculation for one station

Circle drawn on map with station at centre Circle drawn on map at appropriate distance from station Earthquake on that circle (Distance found from) S minus P time

Triangulation

Repeat calculation / drawing with at least three stations Epicentre / earthquake at point of intersection of all three

(or more) circles Triangulation Meaning of triangulation

If no other marks scored Strength greatest nearer earthquake = Level 1 Time shortest nearest the earthquake = Level 1

(6)


Total for Question 6 = 12 marks

0 Level No rewardable content 1 1 - 2 a limited description of process involving isolated fact(s) from one

section.e.g. Circle drawn on map with station at centre OR “triangulation”

the answer communicates ideas using simple language and useslimited scientific terminology

spelling, punctuation and grammar are used with limited accuracy2 3 - 4 a simple description of process involving linked facts from two

sections e.g. the S and P arrival time is recorded, and thedifference noted.

the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

spelling, punctuation and grammar are used with some accuracy3 5 - 6 a detailed description of process involving elements from all three

sections e.g. showing how three stations can identify the epicentreof an earthquake using a calculation and intersecting circles.

the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

spelling, punctuation and grammar are used with few errors


Question Number


2(a)(i) C The Earth is radiating heat to

space

(1)

Question Number


2(a)(ii) An explanation linking any 2 of:

• Hot material rises/cold

material falls (1)

• (causes) material under the

plate to move sideways (1)

• (because of) uneven heating(1)

convection current

in the {mantle/magma/under

plates}

heat from core warms mantle near

core

IGNORE temperature difference (in stem)

(2)

Question

Number


2(b)(i) an explanation linking:

(1) • change in wave speed

• (with) change in

{density/state of the

rock/media/material} (1)

Refraction S-waves reflected

Accept change from solid to liquid or vice versa

IGNORE reference to gas

(2)

Question Number


2(b)(ii) suggestion to include:

• the time difference (1)

• of S and P waves

{arriving/reaching

/detected/recorded}

(same place) (1)

Allow P-waves travel faster ORA for 1 mark, if no other mark scored

(2)


Question

Number


2(b)(iii) • Identifies two points on the

graph

• Evidence of calculation

or comparison to the

equation

• Draws a suitable conclusion

May be scored by points marked on graph

Accept appropriate comment shape of graph e.g. Graph not straight at short distances or Graph nearly straight at long distances

works better for long distances than short distances

(3)



Question Number


3(a) D an ultraviolet wave (1)

Question

Number


3(b) Ultraviolet (from lamp) absorbed

(by fluorescent substance/bank note) (1)

(which) emits {visible/light}

(into eye) (1)

Allow UV for ultraviolet Allow ‘taken in’ for absorbed

Allow ‘given

out’/releases/fluoresces for emits ‘Fluoresces’ on its own is insufficient

Mention of both ultraviolet AND

visible/light only, scores 1 mark

only

(2)

Question

Number


3(c)

Substitution (1)

(Speed =) 6.67 x 1014 x 4.5 x 10

-7

Transposition AND substitution (1)

(time =) 4 x 1016

(6.67 x 1014 x 4.5 x 10

-7

)

Evaluation (1)

1.33 x 108 (s)

Award full marks for correct answer with no working

3 × 108 (m/s) seen anywhere

4 x 1016

3 × 108

ECF candidate’s speed maximum 2 marks

Allow answers which round to 130 000 000

IGNORE Power of Ten error

until evaluation

(3)


Question Number


QWC *3(d) An explanation including some of the following points

• Longitudinal {vibrations/oscillations} are {along/parallel

to/in the same direction as} the direction of {travel/energy

transfer}

• Transverse {vibrations/oscillations} are

{across/perpendicular to/90° to/right angles to} the

direction of {travel/energy transfer}

• Ultraviolet waves are transverse

• Ultrasound waves are longitudinal (ignore sound – not on

list)

• Some seismic waves are longitudinal and some are

transverse

• P waves are longitudinal

• S waves are transverse

• Longitudinal waves need a material for the vibrations

whereas electromagnetic waves can pass through a

vacuum

IGNORE irrelevant material

(6)


Level 0 No rewardable content 1 1 - 2 • a limited explanation of:

EITHER the {vibration/movement} direction and direction of{travel/movement} for transverse or longitudinal waveOR correctly identifying the wave type for at least one examplefrom the list, e.g.

o Longitudinal waves move in the same direction as the wave

moveso Ultraviolet waves are transverse

• the answer communicates ideas using simple language anduses limited scientific terminology

2 3 - 4 • a simple explanation linking:EITHER directions of {vibration/oscillation} and wave travel for bothtypesof waveOR direction of {vibration/oscillation} and wave travel of one typeof wave with at least one example of a wave from the listOR the direction of ‘movement’ and direction of{travel/movement} for transverse AND longitudinal waves ANDcorrectly identifying the wave type for at least one example fromthe liste.g.

o In longitudinal waves the vibrations are in the samedirection as the wave travels. In transverse waves thevibrations are at right angles to the direction the wavetravels.

o In longitudinal waves the vibrations are in the samedirection as the wave travels. Ultraviolet waves aretransverse.

o Longitudinal waves move in the same direction as the wave

moves.Transverse waves move at right angles to the direction thewave moves. Ultrasound waves are longitudinal.

• the answer communicates ideas showing some evidence ofclarity and organisation and uses scientific terminologyappropriately

• spelling, punctuation and grammar are used with some accuracy

3 5 - 6 • a detailed explanation clearly differentiating between the directionsof {vibration/oscillation} for longitudinal AND transverse waves ANDat least one example of each type of wave from the list, e.g.

o In longitudinal waves the vibrations are in the samedirection as the wave travels. In transverse waves thevibrations are at right angles to the direction the wavetravels. Ultrasound waves are longitudinal and ultravioletwaves are transverse.

• the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

• spelling, punctuation and grammar are used with few errors



Question Number


4(a)(i) an ex planation linking: frequency / Hz (1)

above 20 000 (1)

Pitch

too high to be heard by the man

“it is above 20kHz” 2 marks

“The frequency is too loud” gets 1st mark (2)

Question Number


4(a)(ii) substitution: (1) 140/0.42

evaluation: (1) 330

m/s (1)

award full marks for correct answer with no working

allow 333(.333)

independent mark allow ms-1

(3)

Question Number


4(b)(i) A infrasound wave (1) (1)

Question Number


4(b)(ii) arrows to show vibration inopposite directions (1)

parallel to arrow ondiagram (1)

arrows do not have to go through R

horizontal and vertical – no marks multiple directions – no marks

(2)


Question Number


4(c) Explanation linking:

convection (currents) (1)

in mantle (1)

Accept answers in form of a labelled diagram

in molten rock in magma below plates in the hot rock coming from the core under Earth’s crust under surface

ignore lava

clear unlabelled diagram scores maximum 1 mark clear labelled diagram scores maximum 2 marks

(2)

(Total for Question 4 = 10 marks)



Level Edexcel

Subject Physics


Topic Waves



54 minutes

/45

/100

Time Allowed:

Score:

Percentage:



Question Number


1 (a) below 20 Hz (1)

above {20 000 Hz / 20 kHz}(1)

If Hz or kHz is not seensomewhere, the maximumscore is 1 mark.

infrasound

ultrasound

(in either order)

(no units needed for the names) (2)

Question Number


1 (b)(i) C it is a longitudinal wave travelling

faster than an S wave (1)

Question Number


1 (b)(ii) Explanation linking the following:- MP1 refraction /changing speed

(1)

MP2 (due to) changing {material/medium /rock type / density} (1)

ignore changes in direction/ bending (in this case)

rock becomes {more / less} {dense / compact}

(2)

Question Number


1 (b)(iii) Explanation linking the following:-

MP1 (S / transverse waves) they cannot travel through liquid (1)

MP2 Earth’s core is (at least part) {liquid/molten} (1)

MP3 (so) (S waves) they cannot travel through core (to other side of Earth) (1)

Check diagram for creditworthy points.

they can only travel through solids

may be stated in part (ii)

(S / transverse waves) they cannot be detected on opposite side of the Earth to (collision site / earthquake) (3)


Question Number


1 (b)(iv) Suggestion to include any two from:

MP1 idea that {kinetic energy/force/ momentum} of meteor might cause the earthquake (1)

MP2 (earthquakes happen where) plates slide {past/over/under/away from/against} each other (1)

MP3 (plates move) suddenly

MP4 (meteor collision) starts seismic waves /P/S (1)

(meteor) it has large amount of kinetic energy

(earthquakes happen where) plates collide rub/move for slide

(earthquakes happen when) large amount of energy released in / near Earth’s surface

(plates) jolt/jerk

vibrations passing through the Earth condone earthquake waves

{kinetic energy/force /momentum} of meteor can cause the plates to slide past each other = 2

(2)

(Total for Question 4 = 10 marks)


Question Number


2(a)(i) A ultrasound waves have a frequency above 20 000 Hz

(1)

Question Number


2(a)(ii) C sonar (1)

Question Number


2(a)(iii) a description including any two of the following:

• (ultrasound waves /pulses) go down (throughthe water) (1)

• (ultrasound waves are)reflected off fish(1)

• (reflected ultrasoundwaves) are received byboat (1)

• time delay (shows howdeep fish are)(1)

on diagram, wave or ray indicated as downwards idea of wave moving towards or hitting fish

on diagram, waves or rays reflected off fish idea of wave bouncing off fish

signal is timed

ignore fish emitting ultrasound

(2)

Question Number


2(b)(i) (number of waves =) 5 (1) (1)

Question Number


2(b)(ii)2(b)(ii60 ÷ 5 (1) or 60 ÷ (their answer to 2(b)(i)) (1)

12 (cm) or ecf from number of waves

(1)


Question Number


2(c) Substitution 1.7 x 8 (1)

Evaluation 14 (cm/s) (1) 13.6 (cm/s)

give full marks for correct answer, no working

Power of 10 error max. 1 mark.

(2)


Question Number


3(a) D both transverse and longitudinal waves (1)

Question Number


3(b) A description including three of the following points

• molten rock/magma (inmantle) (1)

• convection currents (inmantle) (1)

• plates move (1)• build up of

pressure/force/energy(when plates (not) slidingover/under/past (eachother)) (1)

• sudden movement whenpressure becomes toogreat/is released (1)

• This sudden movement ofplates is an earthquake (1)

Marks can be awarded on a labelled diagram Description of convection currents or arrows on diagram plates rub together

Jolt/jerk when pressure becomes too great/ is released

(3)

Question Number


3(c) relevant values 110 and 10 seen anywhere(1)

100 (s) (1) acceptable range 95 to 105 (s)

(could be on chart)

tolerance +/- 5 s give full marks for correct answer, no working (2)

Question Number


3(d) any vertical line of 10 squares on graph between P- wave and S-wave (1)

OR times eg 52 (s) – 32(s) Range (48 to 56 ) – (29 to 35)

220 (km) (1)

Range 9 to 11 squares

range 200 to 240 (km)


(2)


Question Number


3(e) a description including two of the following:

• longitudinal / sound(wave) (1)

• (frequency) less than 20Hz (1)

Frequency below range/too low for (normal) human ear

(2)


Question Number


4(a) A 23 000 Hz (1)

Question Number


4(b) Any one from the following points

• sonar / ranging (1)

• (medical) scanning(1)

• medical treatment (1)

• animal communication (1)

• cleaning(1)

Accept

foetal/tumours

shattering kidney stones /destroying cancer cells

dog whistles

(1)

Question Number


4(c) An explanation linking the following points

• a reference tofrequency/pitch/hearingrange (1)

• (frequency/pitch) is high(er)for cats RA (1)

[The points must be linked for the second mark]

Accept Hz

Cat detects high(er) frequency/pitch for 2 mark

ignore incorrect value of frequency for ultrasound if a comparison made (tested in 1a)

cat can hear >20000 Hz (2)

humans cannot hear > 20000 Hz / ORA (2)

amplitude too low / too quiet is 1 mark only if no other marks awarded (2)


Question Number


4(d)(i) substitution (1) 340 x 0.047

evaluation (1) 16 (m)

15.9(8) (m)

give full marks for correct answer, no working (2)

Question Number


4(d)(ii) Any two from the following points

• Idea of speed (1)

• correct difference identifiede.g. sound slower RA (1)

It/ infrared/light/em waves travel(s) faster/quicker scores 2 marks

Ignore references to time (2)


Question Number


5(a) A description including the following points

• (Particles) vibrate/oscillate(1)

• (vibration) parallel todirection of wave /propagation (1)

Both marks may be awarded for a clear diagram

move backwards and forwards/to and fro/ push and pull Accept idea of (a series of) compressions and rarefactions

in the same direction as wave travel /energy transfers

Accept they vibrate in the same direction that the wave is going (for 2 marks) (2)

Question Number


5(b) B the frequency of infrasound is too low (1)

Question Number


5(c)(i)

transposition (1) t = distance ÷ speed

substitution (1) (2 x )2500 ÷ 340

evaluation (1) 14.7 (s)

This is a “show that” question, there must be evidence of calculation

Ignore factor of 2 until final evaluation 2500 ÷ 340 = 2 marks

14.7 is evidence of calculation = 3 marks

There are other ways to use the data e.g. 5000 ÷15 = 333 (m/s) (which is about 340 m/s) 2500 ÷7.5 = 333 (m/s) (which is about 340 m/s) OR 340 x 15 = 5100 (m) (which is about 5000 m) Give marks for transposition, substitution and evaluation clearly shown

(3)


Question Number


5(c)(ii) Any one of the following points

• idea of a conversation (1)

• (4000 m is) a longerdistance taking a longertime (to reach otherelephant) (1)

• time needed for waves totravel is about 24 s (1)

• time gap between calls(sufficient) for elephant tohear a reply (1)

• call lasts long enough to beidentified by other elephants(OWTTE) (1)

longer distance and call takes (some) time

waiting to see if there is a reply/response (from another elephant)

(1)

Question Number


5(d) A description linking the following points

• detecting/ locating/monitoring (infrasound) (1)

• volcanic eruptions /underground explosions /earthquakes /nuclearexplosions / meteor strikes(1)

Ignore references to ultrasound and infrared

idea of need for a detecting instrument (1)

idea of infrasound (waves) travelling through a medium (1)

(2)



Level Edexcel

Subject Physics


Topic Waves



60 minutes

/50

/100

Time Allowed:

Score:

Percentage:



Question Number


1(a) D(1)

Question Number


1(b) A description including two of the following

• (bat) emits /sends /makes(ultra)sound /it /signal/wave(1)

• signal/wave /(ultra)soundreflects/bounces(back)/rebounds (off moth/prey)(1)

• bat’s (ears) detectreflected (ultra)sound (1)

• reflection is used toestimate distance (tomoth) (1)

On diagram idea of something emitted e.g. line (with arrow) from anywhere on /near bat or outgoing waves

On diagram idea of something reflected e.g. line with arrow from anywhere on /near moth or reflected waves (from moth)

idea of reflection detected e.g. bat hears the reflected (ultra)sound/wave/signal

idea of bat analyses data e.g. bat times how long (it takes) for reflected wave to get back

Ignore idea that it listens for noises from prey (2)


Question Number

Indicative content Mark

QWC *1(c) A description linking some of the following

• ultrasound does not cause damage to (healthy) cells / ORA• idea of real-time image with ultrasound• ultrasound uses non-ionising radiation• idea that (consultant) can change image position during

ultrasound scan• 3D image possible with ultrasound• ultrasound safer for consultant• ultrasound machines more portable• ultrasound can be used to measure blood flow rates• ultrasound gives detail of soft tissue• X-rays are more suitable for bony structures• X-rays produce higher resolution images• X- rays are more suitable for parts of body containing gas

(lungs, intestines)This list is not exhaustive. Give credit for other plausible suggestions (6)

Level 0 No rewardable material 1-1 • a limited description with no comparison or contrast ie describes

a use/fact about ultrasound OR X-rays eg Ultrasound can be used to look at a foetus (unborn child)

• the answer communicates ideas using simple language and useslimited scientific terminology

• spelling, punctuation and grammar are used with limited accuracy 3-2 • a description giving some attempt at comparison or contrast ie

describes a use of ultrasound AND X-rays eg Ultrasound can be used to look at a fetus. X-rays are used to detect broken bones OR Ultrasound can be used to look at a fetus because it’s safer (than X-rays)

• the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

• spelling, punctuation and grammar are used with some accuracy3 5 - 6 • a detailed description with clear comparison and/or contrast ie

describes a use of ultrasound AND X-rays, one of which is detailed, AND a clear comparison Ultrasound can be used to monitor a fetus. In ultrasound the waves reflect off soft tissue. X-rays (are used to look at bones because they) are absorbed by bones OR Ultrasound can be used to monitor a fetus. In ultrasound the waves reflect off soft tissue. X-rays are used to look at bones but not used for fetus because they can damage DNA/cause mutations of cells

• the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

• spelling, punctuation and grammar are used with few errors


Question Number


1 (d) substitution (1) 5000 x 0.000 003

evaluation (1) 0.015 (m)

evidence of dividing by 2 (1) (5000 ÷2) x 0.000003

scores 3 7.5 x 10-3 (m) marks

ignore powers of 10 until evaluation

e.g. 5000 x 0.0003 etc gains 1markor .15 /1.5/15 etc gains 1mark

1.5x 10-2/ 0.015 gains 2 marks

gains 7.5/0.75/0.075 etc 2

0.0075 (m) scores 3 marks



Question Number


2(a) D (1)

Question Number


2(b)(i) (sudden) decrease in speed refraction / change direction

(1)

Question Number


2(b)(ii) a description linking

• the (speed) increases (1)

with any one of

• as depth increases (1)

• linearly (1)

• from 11.8 to 14 (km/s) (1)

• by 2.2

accelerates

travels further into the mantle / material becomes more dense

steadily / evenly

from >11 and < 12 to >13 and <14

2 to 3 (2)

Question Number


2(b)(iii) substitution (1) 12 = 5800 ÷ t

transposition (1) t = 5800 ÷ 12

evaluation (1) 480 (s)

Substitution and transposition can be in either order

8 minutes A value which correctly rounds to 480



Question Number


2(c) an explanation linking

• impossible to predictearthquakes (1)

with one of • (because) no pattern to

{results/forces} (1)

• (because) not able topredict force needed tomake block start sliding (1)

• the movement of (tectonic)plates is similar to themovement of the block(over the rough surface) (1)

difficult to predict

results {(very) different/not (very) close/not concordant}

as force needed for plates to start sliding is unpredictable

(ignore references to strength of earthquake)

(2)


Question Number


3 (ai) D ultrasound waves (1) (1)

Question Number


3 (aii) Any 3 from

• emits (high frequency/ultra)(sound)(1)

• (sound is) reflected (off fish)(1)

• (reflection) detected by Dolphin(1)

• dolphin (estimates) time between(sending and receiving) sounds (1)

• dolphin is able to change time into(estimate of) distance (1)

Makes/sends out/produces (ultra sound/signal/wave)

Uses ‘high frequency sound’ is insufficient

(sound) bounces off (fish) or echoes

towards dolphin

1st three marks can be scored on the diagram. ie unless stated otherwise, assume any waves/rays starting at dolphin are ultrasound. Rays do not need to be straight

(3)



Question Number


3 (b) An explanation including:

• Infrasound (1)

Plus one from: • Decrease/change in

amplitude is least (1)

• can be detected/’heard’further away (1)

Marks are independent

Stays the biggest/stays high.

Has a bigger amplitude

would travel the furthest/further

(2)

Question Number


3 (ci) B seismic waves (1) (1)

Question Number


3 (cii) (there is a) difference/change in density (1)

more/less/too dense

(reach a) boundary (between different materials)

Ignore ‘the waves cannot travel through liquids/oil’

(1)

Question Number


3 (d) Substitution into correct equation(1) v = 15 x 125

Evaluation (1) 1875

Unit (1) m/s

Power of 10 error max 1 mark for numerical answer

2 marks for correct numerical answer even with no working shown

ms-1 not mps

1.875 km/s or 6750 km/h gain 3 marks

If numerical answer incorrect, accept any correctly-written unit of speed: eg km/s or km/hr or miles per hour / mph

(3)


Question Number


4(a)(i) D (1)

Question Number


4(a)(ii) moons (1)

heliocentric (1)

must be in correct order

(2)

Question Number


4(a)(iii) A description including two of the following points

Reflecting telescope has mirror(s) (1)

Galilean telescope has only lenses (1)

Reflecting telescope can gather more light / can have a larger objective (1)

Image viewed from the side of reflecting telescope (1)

Image viewed from end of Galilean telescope. (1)

refracting telescope

reverse argument (2)

Question Number


4(b)(i) 5 (cm) (1)

8 (cm) (1)

+5-5

0.08 m 80 mm

(2)

Question Number


4(b)(ii) B (1)


Question Number


5(ai) A (1)

Question Number


5(aii) A description linking

plates move / slip / separate (relative to each other) (1)

sudden (release of energy) (1)

plate rubs against each other friction between plates plate boundary shifts

jerk / jolt

(2)

Question Number


5(bi) substituti (on 1) 0.65 = 80 / t

transposition (1) t = 80 / 0.65 (123 seconds)

transposition and substitution can be in either order . Allow reverse calculations eg speed = 80/120 (1) = 0.67 ( about 0.65) (1) or distance = 0.65 x 120 (1) = 78 km (about 80) (1).

(2)

Question Number


5(bii) A description linking any three

detection of arrival of P and S waves (1) measurement of difference in arrival times (1) calculation of distance (from epicentre to station) (1) triangulation/using three / several stations (1)

Reward suitable labelled diagram (3)


Question Number


5(b)(iii) A suggestion including any two of the following

Infrasound (1)

some animals can hear waves below human frequency range / 20 Hz (1)

they could hear P waves arriving before the (stronger) S waves arrive (1)

Some animals have greater audio / tactile sensitivity than humans

(2)



Level Edexcel

Subject Physics


Topic Waves



57 minutes

/47

/100

Time Allowed:

Score:

Percentage:



Question Number


1(b)(i) An explanation linking the following

• the earthquake will be one ofthe points of intersection (1)

• (but) there are two points (ofintersection) (1)

(might implies) further evidence needed possibly at a different place (NOT places)

50:50 chance (2)

Question Number


1(b)(ii) any arrow clearly indicating the common point of intersection ignore ambiguous arrows

a small circle or cross at the common intersection

(1)

Question Number


1(c) • S- wave arrives at 17minutesP-wave arrives 9.5 minutes(1 for both)

• difference in arrival time =7.5 (minutes) (1)

7.0 to 8.0 inclusive 7.30/7:30 give full marks for correct answer, no working

e.c.f from readings marked on graphor stated for a different distance ongraph

(2)

Question Number


1(a) C (1)

Question Number


1(d) A description including the following

• vibration (1)

• in same direction aswave/energy moves (1)

up and down/side to side/shake

backwards and forwards/back and forth scores 2 (2)

P

Q

R


Question Number


2(a) A (1)

Question Number


2(b)(i) (number of waves =) 7 (1)

(distance between floats =)7 × 0.8 (1)

Accept 5.6 (m) give full marks for correct answer, no working e.c.f from number of waves if clear

6.4 (m) for 1 mark (2)

Question Number


2(b)(ii) C (1)

Question Number


2(b)(iii) Any one from the following points

• size (1)

• mass (1)

• speed (1)

• direction of travel (1)

small light slow fast momentum how far away weight power ke (1)

Question Number


2(c)

• change of direction (1)

• towards the normal (1)

• λ shorter than in deep water(1)

Ignore reflection

of EITHER ray or wave

must not reach normal if ray and wave contradict then no mark

λ shorter for all complete waves in shallow water, at least 2 λ drawn, judge by eye (3)


Question Number


3(a) C (1)

Question Number


3(b) 5 (cm) 5.0, +5, -5, ±5 ignore unit (1)

Question Number


3(c) • A difference in f or λ(however described) (1)

This difference correctly qualified by one of

• Relationship to each other(1)

• Relationship to audible sound(1)

• Frequency or wavelengthdata (1)

Accept pitch for frequency

IS has longer λ than audible (1)

US>20kHz (1)

IS has lower f (than US) (2 marks)

information shown on a labelled sketch of the sound spectrum (2)

Question Number


3(d) An explanation linking the following points

• corks as plates /water as mantle (1)

• water heated (underneath)(1)

• convection currentsmentioned(1)

labels on diagram

corks as crust / water as magma /lava

reference to heat in the Earth

arrow on diagram (3)


Question Number


3(e) An evaluation linking the following points

• (a)statement about eitherdistance travelled or arrivaltimes of any two waves (1)

• (b)statement comparing anypair of S-P times (1)

• correct comparison between(a)a) and(b)leading tconclusion (1)

quantitative or qualitative

quantitative or qualitative

quantitative

e.e.g.

station M is twice as far as station L, the S-P time is double, suggestion is OK. 3 marks

e.e.g.

station N is (about) 3½ times as far as station L, but S-P time is 3⅓ times, so maybe not. 3 marks (3)


Question Number


4(a)(i) 12/3 (1)

4 (m) (1)

the wave shown is for 3 wavelengths any correct ratio


(2)

Question Number


4(a)(ii) all amplitudes smaller (1)

all wavelengths longer (1)

Accept smaller peak to trough distance wherever it is drawn

all wavelengths shown must be longer than original can be any shape must be at least half a wavelength shown

(2)

Question Number


4(b)(i) {P-wave / ultrasound / infrasound / shock} (1)

P/primary/pressure (wave)

IGNORE slinky/spring/push-pull (1)


Question Number


4(b)(ii) Any two from:

vibrations different direction (1)

In longitudinal (vibrations) move in same direction as {wave/energy} moves (1)

In transverse (vibrations) move at right angles to direction {wave/energy} moves (1)

In one is up and down, other is backwards and forwards / any two different motions

AND

in longitudinal (particles) move backwards and forwards

in transverse (particles) move up and down/ side to side

(2)

Question Number


4(c)(i) B (1)

Question Number


4(c)(ii) substitution (1) ie 340 / 1047

evaluation (to at least 2 sf) (1) ie between 0.32 and 0.33 (m) inclusive

conversion of m to cm (1)

No RA

If incorrect value chosen for frequency cannot get substitution mark but can get evaluation mark and conversion mark frequency (Hz) evaluation(m) 1290 0.26

0.27 0.28 0.29 0.31

1245 1200 1174 1109 960 0.35

(3)


Question Number


5(a)(i) B (1)

Question Number


5(a)(ii) An explanation linking two of the following:

• (uneven) heat (from thecore) (1)

• convection (currents) (1)

• (that are in) the mantle(1)

(2)

Question Number


5(b) C (1)

Question Number


5(c)(i) Description to include:

• (they can be) reflected (1)• (and/or) refracted (1)

bounce off/back change direction/speed

(2)

Question Number


5(c)(ii ) Substitution (1)

1200/200

Evaluation (1)

6 (km/s) Power of 10 error max 1 mark


(2)

Question Number


5(d) An explanation linking

• tsunamis are caused byunderwater earthquakes /volcanic eruption (1)

• are random/irregular (1)

Underwater movements of the plates / landslip into the sea / meteorite strike into the sea

can happen at any time / do not know when it will happen (2)



Level Edexcel

Subject Physics


Topic Waves



56 minutes

/46

/100

Time Allowed:

Score:

Percentage:



Question Number


1(a)(i) B (1)

Question Number


1(a)(ii) An explanation linking

• {X- rays are / ultrasoundis not} dangerous (1)

• (because X-rays) can{damage / harm} {tissue/ DNA} ORmutate cellsORreverse argument forultrasound (1)

X-X-rays are ionisingultrasound is not ionisingignore penetration/penetratingignore bald harm / harmful forMP1Ignore reference to frequencyand energy

X-rays cause cancerignore foetus / baby / bodyIgnore unqualified ‘mutation’

(2)

Question Number


1(b) (i) 30 000 Hz / hertz 30 kHz 0.03 MHz unit must be included (1)

Question Number


1(b)(ii) A description including

particles {vibrate / oscillate} (1)

(move) in the {same direction as / parallel to the direction } the wave travels (1)

‘they’ refers to particles

to and fro back and forth ignore all up and down and side to side references

Both points could be shown on a clear diagram with arrows or labels (e.g. compressions and rarefactions)

(2)


Question Number


QWC *1(c) An explanation including some of the following points • sonar is ultrasound• travels through water at the speed of sound (1500 m/s)• ultrasound signal generated in the ship• signal emitted from the bottom of the ship• signal travels down through the water• strikes shoal of fish• signal reflected by fish• reflected signal detected on the ship• time between emission and detection measured• either time halved and depth of fish calculated /or

distance wave travelled calculated and halved to givedepth of fish

• calculation done using x = v x t• comparison of depths of fish and of seabed

(6)

Level

0 No rewardable content

1 1 - 2 • a limited explanation e.g. A sonar wave (ultrasound pulse) goesdown and is reflected. OR An ultrasound pulse is sent from theboat and timed.

• the answer communicates ideas using simple language and useslimited scientific terminology.

• spelling, punctuation and grammar are used with limited accuracy.2 3 - 4 • a simple explanation e.g. An ultrasound signal goes down through

the water and is reflected AND the time taken is measured.• the answer communicates ideas showing some evidence of clarity

and organisation and uses scientific terminology appropriately.• spelling, punctuation and grammar are used with some accuracy.

3 5 - 6 • a detailed explanation e.g An ultrasound signal is emitted andreflected. The time is measured AND depth is found by halving(the total time or the total distance) AND linking to either thespeed equation or the speed of the wave or the depth of fishcompared to sea depth.

• the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately.

• spelling, punctuation and grammar are used with few errors.


Question number

Answer Mark

2(a) An answer that combines the following points of understanding to provide a logical description:

• use a stopwatch (1)• start timing when flash is seen and stop when bang is

heard (1) (2)

Question number

Answer Mark

2(b)(i) A (1)

Question number

Answer Mark

2(b)(ii) C (1)

Question number

Answer Additional guidance Mark

2(c)(i) electromagnetic wave allow any named e.m. wave/seismic S wave

(1)

Question number


2(c)(ii) sound wave allow ultrasound/infrasound/ seismic P wave

(1)

Question number


2(d) two minutes = 120  s (1)

substitution (1) 26  400 ÷ 120

answer (1) 220 (m/s)

ecf unit change

award full marks for correct numerical answer without working

(3)


Question number

Answer Mark

3(b)(ii) A (1)

Question number

Answer Mark

3(b)(iii) D (1)

Question number

Answer Mark

3(a) An answer that provides a description by making reference to:

• transverse waves have oscillations perpendicular todirection of travel of the wave (1)

• whereas longitudinal waves have oscillations in thesame direction as the direction of travel of the wave (1) (2)

Question number

Answer Mark

3(b)(i) An answer that combines the following points of understanding to provide a logical description:

• take time T for waves to pass a fixed point (1)• and frequency = number of waves

time taken (1) (2)


Question Number


4 (a) B

(1)

Question Number


4b(i) A description including three of the following points

• reflection (of light) at(either) mirror (1)

• (the curved mirror) focusesthe light (1)

• (mirror) inverts (1)

• (lens / eyepiece) magnifiesimage (1)

• image is formed where thelight rays cross (1)

Bounces for reflects

flips it over/turns over

lens/eyepiece refracts light

Image is real(1)

Accept for 1 mark if no other mark awarded: (Telescope) reflects and refracts light (1) (3)

Question Number


4(b)(ii) An explanation including two from

• collects more light (1)

• produces amagnified/bigger image(1)

• shows more detail (1)

• shows stars the naked eyeis unable to see (1)

• can observe stars day andnight (1)

brighter

looks closer/zooms in

makes it clearer/better

see further/more (stars)

(2)


Question Number


4(c)(i) transverse (wave) mechanical (1)

Question Number


4(c)(ii) move up and down a bigger distance (1)

Question Number


4(c)(iii) substitution (1) 4 x 0.5

evaluation (1) 2 (m/s)

give full marks for correct answer, no working Accept power of ten error for 1 mark eg. 0.2, 20, 200, 2000 (2)


Question Number


5(a)(i) An explanation linking the following points

• 15 % of power /energy (1)

• is transferred usefully (1)

Accept reverse argument

• 85% of power / energy (1)

• is wasted (1)

15 W / 15 J/s / 15 J

transferred as light converted into useful energy/ is not wasted

(2)

Question Number


5(a)(ii) • two qualitative output labels

(1)light (energy) and thermal/heat (energy)

• a quantitative output label(1)15 J for light/used /usefulor on narrower arrow (ofotherwise unlabelled Sankeydiagram)

useful/used (energy) and wasted (e

85 J for heat/wasted or on broader arrow (of otherwise unlabelled Sankey diagram)

(2)


Question Number


5(b) Any two of the following reasons

• Energy, e.g. (low-energylamps) are more efficient /waste less energy / produceless heat (1)

• Economy, e.g. (low-energylamps) use less electricalenergy /cost less to run /have a lower power (rating)(1)

• Environment, e.g. using(low-energy lamps) reducesCO2 emissions / saves fossilfuel (1)

• Practical, e.g. (low-energylamps) last longer / needreplacing less often / (canbe) easier to obtain (1)

Accept reverse arguments

Accept ‘they’ for low-energy lamps

idea of Payback, e.g. (low-energy lamps) are (more) cost effective (over time)

Ignore unqualified environment statements

filament lamps (have been) banned (in some countries)

(2)

Question Number


5(c) An explanation linking these three points

• energy gain is from powersupply(1)

• energy loss is byradiation(1)

• the loss and the gain areequal /at the same rate(1)

energy (comes) from the mains / supplied with electrical energy

thermal/heat energy emitted infrared emitted

the loss and gain are in equilibrium

allow the filament gains and losses energy for (1) only (3)



Level Edexcel

Subject Physics


Topic Waves



24 minutes

/20

/100

Time Allowed:

Score:

Percentage:



Question number

Answer Mark

1(a)(i) An explanation that combines identification via a judgement (1 mark) to reach a conclusion via justification/reasoning (2 marks):

• galaxy C has the greatest red shift (1)• so this galaxy has the greatest speed (1)• since the galaxy with the greatest speed will be

furthest away, then galaxy C is at the furthestdistance(1) (3)


Question number


1(a)(ii) 20 (nm) Allow answers in the range 19 to 25

(1)

Question number


1(a)(iii) Substitution (1)

( )98 20×10v

−3 10× ) (×=

(390×10−9 )

Answer (1)

= 15  400  000  (m/s)

allow ecf from (c)(i)

power of 10 error = max 1

accept 15  384  615  (m/s)


(2)

Question number


1(b) Any two from the following improvements:

• use wider aperturetelescope/camera (1)

• better quality objectivelens (1)

• use longer exposuretime while telescope islocked onto star (1)

• move telescope to betterseeing conditions, e.g. drydesert, higher up amountain, dark skies (1)

allow

improvements from photography, e.g. use longer exposure time

use a satellite telescope

ignore use pc to adjust the sharpness of the image

(2)


Question number


2(a) An explanation that makes reference to: identification – knowledge (1 mark) and reasoning /justification – knowledge (1 mark):

• the wavelengthdecreases becausewavelength is the ratioof wave velocity tofrequency (1)

• and the wave velocityreduces at the boundarybut the frequencyremains the same (1)

allow the same number of waves per second arrive at the boundary as leave it for no change in frequency at the boundary (2)

Question number

Indicative content Mark

2(b) Answers will be credited according to candidate's deployment of knowledge and understanding of the material in relation to the qualities and skills outlined in the generic mark scheme. The indicative content below is not prescriptive and candidates are not required to include all the material which is indicated as relevant. Additional content included in the response must be scientific and relevant.

AO1 (6 marks) • point A reaches the glass block before point B• A moves into the glass block and slows down• as light travels more slowly in glass than in air• B is still in air so is travelling faster than A• this causes part of the wavefront to change direction/refract• by the time B reaches the block it will have travelled further

than A• therefore, the whole wavefront changes direction/refracts

towards the normal• at the other face, A exits first so the process is reversed• the wavefront changes direction again so it is parallel to its

original direction/refracts away from the normal (6)


Level Mark Descriptor

0 No rewardable material.

Level 1 1–2 • Demonstrates elements of physics understanding, some ofwhich is inaccurate. Understanding of scientific ideas lacksdetail. (AO1)

• Presents an explanation with some structure and coherence.(AO1)

Level 2 3–4 • Demonstrates physics understanding, which is mostlyrelevant but may include some inaccuracies. Understandingof scientific ideas is not fully detailed and/or developed.(AO1)

• Presents an explanation that has a structure which is mostlyclear, coherent and logical. (AO1)

Level 3 5–6 • Demonstrates accurate and relevant physics understandingthroughout. Understanding of the scientific ideas is detailedand fully developed. (AO1)

• Presents an explanation that has a well-developed structurewhich is clear, coherent and logical. (AO1)

Question number


2(c) Substitution into v = st

to find v (1)

1.5×1011v =500

Substitution into v = f ×λ and unit conversion (1)

1.5×1011

500v = = f × 670 × 10−9

Transposition (1) Rearrangement (1)

( )( )

11

9

1.50×10

500 670× ×10f

−=

Answer (1) 4.5 x 1014 (Hz)

s is distance


maximum 3 marks if λ in nm

4.4776 x 1014 (Hz)

(4)


Properties of Waves - Merit Tutors · 2018. 5. 25. · Properties of Waves Mark Scheme 2. Level...

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