Induction Quiz.pdf

Induction Quiz:
Change your field and see a new current understanding!
emf = V = IR = ∆{ NBA/t } F= BIL=qVB
1. Changing the magnetic field intensity “B “ in a closed loop of wires induces
A) resistance B) voltage.
C) light D) magnetism
2. Electric current can best be induced in a wire by
A) setting the wire near a magnet.
B) moving a magnet up and down near the wire.
C) rotating the wire in the air
D) screaming at the wires in a high pitch, “charge!”
3. A magnet is moved in and out of a coil of wire connected to a high-resistance
voltmeter. If the number of coils doubles, the induced voltage
A) quadruples. B) doubles.
C) is the same. D) halves.
4. The phenomenon of inducing voltage by changing the magnetic field around a
conductor is called
A) emf- electromotive force B) Faraday’s French Fries
C) emagnetic radiation. D) transformer multiplication
5. A device consisting of a coil that is mechanically rotated in a stationary magnetic
field to create voltage
A) a transformer. B) a motor.
C) a generator D) a dipole.
6. A generator is used to light a bulb. Energy for lighting the bulb actually comes
from a
A) coil of wire.
B) mechanical work-energy put into the generator.
C) magnet in the generator.
D) plug where the generator is connected to the wall.

7. The magnetic field strength inside a current carrying coil will be greater (more
focused) if the coil encloses a
A) vacuum. B) wooden rod.
C) glass rod. D) iron rod.
8. A device that transforms electric energy to mechanical energy is a
A) generator. B) motor.
C) transformer. D) magnetometer.
9. The principal reason voltage is induced in the loops of a generator coil is that the
A) the amount of magnetic field within the loops is changing
B) the wires have very low resistance
C) strong magnets create voltage at their poles
D) magnetic elves push the loops and yell power to the little people!
10. Most commercial generators (including in Illinois) are driven by the power of
A) wind. B) steam
C) falling water. D) illegals running home
11. A device that uses two coils around an iron core to change the voltage across a
circuit is called a
A) voltmeter. B) motor
C) transformer. D) generator.
12. If the primary coil of a transformer were connected to a dc power source, the
transformer would operate
A) slowly and then stop B) the same as always.
C) only at very high dc voltages D) not at all – no voltage produced
13. An electric motor and an electric generator are
A) essentially the same device, but run in opposite directions
B) entirely different devices- you can’t make one from the other
14. A transformer transforms
A) magnetic field lines. B) generators into motors.
C) dc voltage into ac voltage. D) voltage.

15. A step-up transformer
A) decreases voltage. B) increases voltage.
C) increases power D) decreases power
16. The principal advantage of ac power over dc power is that
A) less energy is dissipated during transmission.
B) ac voltage can be transformed more easily.
C) ac circuits multiply power more easily.
D) ac circuits are safer.
17. The primary coil of a transformer has 100 turns on it and the secondary coil has
50 turns on it. This is
A) a step-up transformer.
B) a step-down transformer.
C) Either of the above depending on relative input and output currents
18. The voltage across a transformer primary coil that has 100 turns is 10 V. What
is the voltage across the secondary coil, which has 20 turns?
A) 100 V B) 50 V
C) 10 V D) 2 V
19. Which is the unit for magnetic flux “B” ?
A)Voltage
B) Tesla
C) kilowatt-hours D) amps/m2
20. Almost all energy sold today is of the ac type because
A) ac voltage is easy to step up and step down.
B) dc voltage requires resistors which get hot and are less efficient
C) ac voltage is safer since low currents can be used
D) all of the above
21.A certain transformer doubles input voltage. If the primary coil has 10 A of
current, then the current in the secondary coil is
A) 2 A. B) 5 A.
C) 10 A. D) 20 A.
22. The meter used for your electric bill measures kilowatt-hours which is
A) power B) energy
C) charge D) emf

23. What direction is the force, if B is into the page and I is south?
A)top of page
B) bottom of page
C)left
D) right
E) in page F) out of page
24. What direction is the field if F is into the page
and a positive charge moves south?
A)top of page
B) bottom of page
C)left
D) right
E) in page F) out of page
25. Imagine a solenoid of wire standing up on its long end.
What direction is magnetic field for the current shown?
A)up
B) down
C)clockwise
D) counter clockwise
E) in page F) out of page