The fact that a current carrying wire deflects a compass needle is evidence that

Question 1 options:

1) 

the wire is magnetized

2) 

the north pole of the earth has shifted

3) 

the compass needle has an electric charge on it

4) 

the current gives rise to a magnetic field
Question 2 (1 point) 

Listen
The force of an electron moving in a magnetic field will be the largest when it's direction

Question 2 options:

1) 

is the same as the magnetic field direction

2) 

is exactly opposite to the magnetic field direction

3) 

is perpendicular to the magnetic field direction

4) 

is at an angle other than 90 degrees to the magnetic field direction
Question 3 (1 point) 

Listen
Two parallel wires, each carrying a current I, repel each other with a force F. If both currents are doubled, the force of repulsion is

Question 3 options:

1) 

4√2 F


2) 

2F


3) 

8F


4) 

2√2 F


5) 

4F

Question 4 (1 point) 

Listen
A charged particle with constant speed enters a uniform magnetic field whose direction is perpendicular to the particles velocity. The particle will:

Question 4 options:

1) 

Experience no change in velocity


2) 

Follow a parabolic arc 


3) 

Slow down


4) 

Speed up


5) 

Follow a circular arc

Question 5 (1 point) 

Listen
A piece of wire carrying a current of 5.0A is bent into a loop with radius 35cm.  What would be the magnetic field strength at the center of the loop?

Question 5 options:

1) 

Cannot be solved with given values.


2) 

1.4X10-6 T


3) 

1.1X10-6 T


4) 

8.9X10-6 T

Question 6 (1 point) 

Listen
A segment of wire 20cm long is carrying a current of 5.0A and runs at an angle 30° off from perpendicular with a magnetic field of 3.0X10-3 T.  What is the magnitude of the force acting on the wire segment?

Question 6 options:

1) 

2.6X10-2 N


2) 

1.9X10-4 N


3) 

3.0X10-3 N


4) 

2.6X10-3 N

Question 7 (1 point) 

Listen
A negatively charged particle in a uniform magnetic field B moves with constant speed v in a circular path of radius r, as shown. Which of the following graphs best represents the radius r as a function of the magnitude of B, if the speed v is constant?


Question 7 options:

1) 




2) 




3) 




4) 




5) 



Question 8 (1 point) 

Listen
A current of 12 A in a solenoid of length 0.35 m produces a magnetic field strength of 4.8×10-3 T at the centre of the solenoid. How many turns of wires does the solenoid contain?

Question 8 options:

1.1×102 turns


3.2×102 turns


1.3×103 turns


1.6×104 turns

Question 9 (1 point) 

Listen
A proton traveling at 2.4×105 m/s enters a uniform magnetic field. The path of the proton in the magnetic field is a circle of radius 5.6×10-3 m. If the path of the proton is perpendicular to the magnetic field, what is the strength of the magnetic field?

Question 9 options:

2.4×10-16 T


0.45 T


2.2 T


4.3×1015 T

Question 10 (1 point) 

Listen
An aircraft carries a static charge of 0.60 C. It travels at 240 m/s perpendicular to a 1.5×10-4 T magnetic field. What magnetic force does the aircraft experience?

Question 10 options:

0.022 N


0.060 N


0.54 N


9.6 ×105 N

Question 11 (1 point) 

Listen
A solenoid has a length of 0.30 m, a diameter of 0.040 m and 500 windings. The magnetic field at its centre is 0.045 T. What is the current in the windings?

Question 11 options:

2.9 A


3.0 A


21 A


370 A

Question 12 (1 point) 

Listen
How fast must tan electron travel in order to pass undeflected through the crossed electric (5.0 x 103N/C) and magnetic fields (1.2 x 10-3T) if it is moving perpendicularly to both.

 

Question 12 options:

1) 

6.0 m/s


2) 

4.2X106 m/s


3) 

8.4X106 m/s


4) 

5.3X105 m/s

Question 13 (1 point) 

Listen
A positive electric charge of negligible weight is released from rest between the poles of a horseshoe magnet as shown. What would be the direction of the acceleration of the charge caused by the magnetic field?


Question 13 options:

1) 

downwards


2) 

towards the south pole


3) 

none of the above


4) 

upwards


5) 

towards the north pole

Question 14 (1 point) 

Listen
The diagram shows the polarity of a coil connected to a battery. The terminals of the battery are indicated by X and Y.

 



On the basis of the information given, which one of the following conclusions is correct?

Question 14 options:

1) 

electrons flow through the coil from end S to end N

2) 

Y is the negative terminal of the battery

3) 

there is no magnetic field outside the coil

4) 

the coil is wound on a core material with high permability

5) 

the magnetic field lines inside the coil point from N to S
Question 15 (1 point) 

Listen
A particle of charge +e and mass m moves with speed v perpendicular to a uniform magnetic field B directed into the page. The path of the particle is a circle of radius r, as shown.

The period of revolution of the particle is


Question 15 options:

1) 




2) 




3) 




4) 




5) 



Question 16 (1 point) 

Listen
A 120 V motor draws 12 A when running at 3200 RPM. When the motor armature is momentarily stopped the current increases to 30 A. What is the resistance of the armature?

Question 16 options:

1) 

4.0

2) 

6.0

3) 

10.0

4) 

14.0
Question 17 (1 point) 

Listen
An electric motor with resistance 5Ω is known to have a back emf of 60V.  The current when running normally is 3A.   What is the normal voltage rating of this motor?

Question 17 options:

1) 

75V


2) 

15V


3) 

45V


4) 

80V

Question 18 (1 point) 

Listen
What is the back EMF of a 120 V motor which draws 9.5 A while running and 25 A when the motor shaft is stopped and the 120 V is still applied?

Question 18 options:

1) 

4.8 V

2) 

46 V

3) 

74 V

4) 

170 V
Question 19 (1 point) 

Listen
An electric motor rotates at various speeds and the current through the armature changes accordingly. Which pair of conditions occurs when the motor generates the greatest back emf?

 



Question 19 options:

1) 

A

2) 

B

3) 

C

4) 

D
Question 20 (1 point) 

Listen
A square loop 15 cm by 15 cm consisting of 12 turns of wire is in a magnetic field of strength 3.3 x 10-3 T with its plane PARALLEL to the direction of the field. Then it is rotated in a time interval of 0.12 s so that its plane is PERPINDICULAR to the direction of the field. What is the average EMF induced in the loop during this interval?

Question 20 options:

1) 

0

2) 

1.1 x 10-4 V

3) 

6.2 x 10-4 V

4) 

7.4 x 10-3 V
Question 21 (1 point) 

Listen
Which of the following is a correct unit for magnetic flux?

Question 21 options:

1) 

Newtons/Coulomb

2) 

Tesla meter2

3) 

Volts

4) 

Tesla
Question 22 (1 point) 

Listen
When a wire moving through a magnetic field has a voltage induced between the wire's ends, that voltage is
I. directly proportional to the strength of the magnetic field
II. directly proportional to the velocity of the wire
III. directly proportional to the diameter of the wire

Question 22 options:

1) 

II and III only


2) 

II only


3) 

I and II only


4) 

I only


5) 

III only

Question 23 (1 point) 

Listen
A magnet is dropped through a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the magnet in the pipe falls:

Question 23 options:

1) 

more quickly because the currents induced in the pipe produce an opposing magnetic field


2) 

more quickly because it is attracted by the innate magnetic field of the pipe


3) 

more slowly because the currents induced in the pipe produce an opposing magnetic field


4) 

more slowly because it is attracted by the innate magnetic field of the pipe


5) 

at the same rate

Question 24 (1 point) 

Listen
The figure shows a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what direction would the magnetic field be in the area contained within the conducting rails?


Question 24 options:

1) 

to the left


2) 

out of the page


3) 

into the page


4) 

to the right


5) 

It is impossible

Question 25 (1 point) 

Listen
A wire of constant length is moving in a constant magnetic field, as shown. The wire and the velocity vector are perpendicular to each other and are both perpendicular to the field. Which of the following graphs best represents the potential differ­ence E between the ends of the wire as a function of velocity?


Question 25 options:

1) 




2) 




3) 




4) 




5) 



Question 26 (1 point) 

Listen
A step-up transformer increases

Question 26 options:

1) 

power

2) 

energy

3) 

both of the above

4) 

none of the above
Question 27 (1 point) 

Listen
Neon signs require about 2,000 volts to operate. If the circuit uses a 120 volt power source, the ratio of primary to secondary turns on the transformer should be closest to:

Question 27 options:

1) 

1:100


2) 

100:1


3) 

1:17


4) 

17:1


5) 

122:1


6) 

1:122

Question 28 (1 point) 

Listen
Four amps of current exist in the primary coil of an ideal transformer. The voltage across the primary coil is 110 V. What is the Power output of the secondary coil?

Question 28 options:

1) 

less than 30 W

2) 

110 W

3) 

440 W

4) 

not enough information to say
Question 29 (1 point) 

Listen
A transformer has 50 primary turns and 375 secondary turns.  It has an efficiency of 82%.  If the secondary current is measured as 1.2A, what is the primary side current?

Question 29 options:

1) 

0.13A


2) 

11.0A


3) 

5.1A


4) 

7.4A

Question 30 (1 point) 

Listen
A straight piece of wire of length 27cm is moving in a plane that is perpendicular to a magnetic field of strength 0.050T.  The speed of the wire is 12m/s, but the angle between the length of wire and the velocity vector is 70°.  What induced EMF will be produced in the wire?

Question 30 options:

1) 

0.055 V


2) 

16 V


3) 

0.16 V


4) 

0.15 V