Magnetic EffectCh.2

1

Chapter 2

(Revision)

Belshefah

Straight Wire

2. All the following Is the equivalent unit to the measuring unit of the Magnetic flux density except ..

a) wb/m² b) N.s/c.m

c) N.A/m d) kg/c.s

3.Which physical quantity measuring by unit Joule/Ampere..

a) Permeability b) Magnetic flux

c) Magnetic flux density d) Torque

1. The unit of ( web/Amp.m) is the measuring unit of …

a) Permeability b) Magnetic flux

c) Magnetic flux density d) Torque

4. What is the physical quantity measuring by unit ohm.coloumb..

a) Magnetic flux b) Magnetic flux density

c) Force d) Torque

5. Two bodies with penetrating magnetic field lines on their surfaces , as the figure shows , if the

magnetic flux for body 1 is ø1 and body 2 is ø2 so..

a) ø1 = ø1

b) ø1= 0.5 ø1

c) ø1= 2 ø1

d) ø1 = 4ø1

Magnetic EffectCh.2

2

6. Two bodles penetrate their surface with magnetic flux lines in perpendicular position ..

a) BB = BA

b) Bb > BA

c) BB < BA

d) BB = BA =Zero

A B

Magnetic EffectCh.2

3

7. A wire perpendicular to the page carries an electric current in direction into the page , The

direction of the magnetic field at point A is ..

8. An electron beam passed in a straight line parallel to straight wire carries a current as the figure

shows , The magnetic density at point A,B ..

a) A>B b) B=A

c) B>A d) no answer

9. A wire carries current in a direction into the page , which point is north direction ..

a) A

b) B

c) C

d) D

Straight Wire Direction

Magnetic EffectCh.2

4

10. Which diagram represents the direction of the magnetic field around a straight wire

carrying a current

11. A magnetic needle placed in the plane and the page next to wire carry current into the page at

point x, at any point the current position of the compass ..

12. Two straight wires perpendicular to the page carries an equal current in a direction into the

page , at any point the direction of the net magnetic field is out of the page ..

a) 1

b) 2

c) 3

d) no correct answer

Magnetic EffectCh.2

5

14. Four long straight wires carry equal currents perpendicular to the page and four compass

takes direction as the figure shows , the deflection of electric current in wires are ..

Into the page Out of the page

a) Wires P,S Wires R,Q

b) Wires P,Q Wires R,Q

c) Wires P,R Wires Q,S

d) Wires Q,S Wires P,R

13. In the opposite figure a wire passes through a current down a magnetic needle directly parallel

to it`s axis when closed key , North pole ..

a) Deflects to east b) deflects to west

c) Rotates and settles south west d) remains constant

Magnetic EffectCh.2

6

16.. In the opposite figure a straight wire carry current I , The Magnetic flux density at points

x, y , z …

a) Bx = By = Bz

b) By > Bx = Bz

c) By = Bz > Bx

d) Bx > By > Bz

15. A straight wire passes through it an electric current I penetrates a rectangular paper

perpendicular as the figure shows , The magnetic flux density B at points …

a) Bx = By = Bz

b) By < Bx

c) By > Bx = Bz

d) Bx = Bz = Zero

17. In the opposite figure two long straight wires carrying same current, if the first one is placed in

the plane of the page , and the second wire perpendicular to the page , the net magnetic flux

density at point A will be ..

a) Zero b) 2B

c) 2 B d) 2 B

Magnetic EffectCh.2

7

19. Two wires perpendicular to the page , if the point P is the neutral point , the value of the current

intensity I1 and it`s direction ..

a) > I2 , into

b)> I2 , out

c) < I2 , into

d) < I2 , out

20. Two wires perpendicular to the page carrying current I1 , I2 ..

If point a is neutral point , the current intensity I2 equals ..

a) 3/2 I1 , into

b) 2I , into

c) 0.5 I1 , out

d) 2/I1 , out

18. Two parallel straight wires A,B carry electric currents I , 2I respectively in the same direction , if

the neutral point lies at distance 10cm from wire (A) , the distance between two wires (d) equals ..

a) 20 cm b) 40 cm c) 30 cm d) 15 cm

Neutral point

Magnetic EffectCh.2

8

Coil and Solenoid

21. When an electron rotates in the circle , produce the magnetic field at the center it’s

direction ………….

a) Into the page b) out of the page

c) Right d) left

22. . In which coil the magnetic flux density at its center equal zero ……………………

23. In the opposite figure , the resultant magnetic flux density at point m ………………….

a) 2 x 10-5 T , out b) 2 x 10-5 T , into

c) 4 x 10-5 T , out d) 4 x 10-5 T , into

El Shamel

Magnetic EffectCh.2

9

24. A wire in the form of a circular loop and carries electric current I and the magnetic flux at its

center is B , if the wire is reshaped to form another circular coil of 5 turns and carry the same

current I , the magnetic flux density at its center become……….

a) 5B b) 25B c) B5

d) 10B

26. In the opposite figure , the resultant magnetic field at point ( m ) …………….

a) 6 x 10-5 T b) 2 x 10-5 T c) 5 x 10-5 T d) zero

25 . Two solenoids ( X ) , ( Y ) that have the same current and the number of turns ( N ) , ( 2N )

respectively , the relation between magnetic flux density B1 at point C and the magnetic flux

density B2 at point d is ……….

a) B2 = 2B1 b) B2 = B1

c) B2 = 1

2B1 d) B2 =

1

4B1

Magnetic EffectCh.2

10

27 . In the opposite figure , the net magnetic field at the center equal …………

a) 10-5 T b) 1.2 x 10-4 T c) 6 x 10-5 T d) zero

28 . In the opposite figure , the net magnetic field at the center equal …………………

a) 0.04 mT b) 0.02 mT c) 0.2 mT d) zero

El Wessam

Magnetic EffectCh.2

11

30.. The electric current intensity passing through that coil 2A , the magnetic flux density at point b

equal …………..

a) 39 x 10-6 T b) 49 x 10-6 T

c) 10 x 10-6 T d) 13 x 10-6 T

29. In the opposite figure , the resultant magnetic flux density at point ( a ) equal …………….

a) 2 x 10-5 T , into b) 2 x 10-5 T , out

c) 3 x 10-5 T , out d) 3 x 10-5 T , out

Magnetic EffectCh.2

12

El Wessam

31 . In the opposite figure the net magnetic flux density at center P ( a = r , b = 2r ) …………

a) 3μI8r

b) 3μI4r

c) 3μI16r

d) 9μI16r

32 . A circular coil divided in two halves , the first half has cross-section area 3 times of the second

half , the total magnetic field at the center equal ………………….

a) μI8r

b) μI6r

c) μI4r

d) Zero

Symbols Only

Magnetic EffectCh.2

13

El Wessam

34 . Two straight wires A,B and 2 turn of a coil is placed in the same plane of the two wires , the

magnetic flux density at its center is B and when the current in wire A reversed , the magnetic

flux density at center ……………

a) Increase of factorBπ

b) Increase of factor πB

c) Increase of factor B2π

d) Become 2B

El Wessam

33 . In the opposite figure , the net magnetic field at point ( a ) ………..

a) 8 x 10-5 T

b) 1.2 x 10-4 T

c) 1 x 10-4 T

d) zero

Coil & Wires

Magnetic EffectCh.2

14

35 . If an insulated long straight wire placed to the left of the cell at distance 20 cm from the

center of the coil , what is the value and the direction of straight wire to make point ( a )

neutral point ……………..

a) 15 I , downward b) 15 I , upward

c) 15 π I , downward d) 15π

I , upward

36 . If an insulated straight wire placed to right of the coil at distance 20 cm from the center of

the coil , what is the value and the direction of the current of the straight wire to make point

( c ) neutral point ……………

a) 29 A , upward b) 9.2 A , upward

c) 29 A , downward d) 9.2 A , downward

Magnetic EffectCh.2

15

37 . A solenoid coil its axis in the direction of earth field of 5 x 10-4 T and the net magnetic flux

density at point A is 2 x 10-4 T , if the direction of the current in a solenoid coil is reversed , the

magnetic flux density at point A become ………….

a) 2 x 10-4 T b) 3 x 10-4 T

c) 7 x 10-4 T d) 12 x 10-4 T

38 . Which diagram represents the net magnetic flux density at center ( m ) equal zero

a) 2 , 4 only

b) 2 , 1 only

c) 2 only

d) 4 , 3 , 2 , 1

Magnetic EffectCh.2

16

Magnetic EffectCh.2

17

42 . Two concentric circles in the same plane carrying current I , 3I . What is the value of the radius

of small circle that makes the magnetic flux density at its center equal zero ……………….

a) 1cm b) 2cm c) 4cm d) 6cm

41 . In the opposite figure , the net magnetic flux density at the center ……

a) 12 x 10-7 T , out b) zero

c) 12 x 10-7 T , into d) no correct answer

39. An insulated two long parallel straight wire is placed in a vertical position such that it becomes

tangent to an insulated circular coil , the group is placed in a horizontal plane , to make the

magnetic flux density at the center of the coil equal zero the direction of the coil should

be………….

a) Clock wise b) anti-clockwise c) equal zero

Neutral Point

Magnetic EffectCh.2

18

Directions

43 . All coils carry the same current , which coil has maximum repulsion force between

coil and magnet .

45 . A magnetic needle placed in the center of the Jaws is a piece of iron , when the key is open

the north pole deflected to …….

a) Right

b) left

c) east

d) west

44 . In the opposite figure a solenoid coil , there is a compass at one end ( Y ) , if the current enters

from point ( X ) to point ( Y ) , what is the direction of deflection of the compass ………….

a) b)

c) d)

Magnetic EffectCh.2

19

47 . A current passes through the coil shown in figure

the kind of pole at terminals ( X ) , ( Y )………..

a) ( X ) North , ( Y ) south b) ( X ) south , ( Y ) North

c) ( X ) North , ( Y ) North d) ( X ) south , ( Y ) south

46 . Two similar coils S1 , S2 are suspended by four wires and two coils free to move ,

what happen when key closed ………….

a) Move right together

b) move left together

c) Attracted together

d) repulsion together