Lesson 9.04 Electromagnetic Induction
Self-Check Quiz
1. An electric generator consists of n = 500 turns of wire formed into
a rectangular loop with a length of 0.05 m and width of 0.03 m placed
in a uniform magnetic field of 2.5 T. What is the maximum value of the
emf produced when the loop is spun at f = 100 rpm about an axis
perpendicular to B?
a. 196.0
b. 144.1
c. 95.3
d. 79.2
e. 60.3
Answer: _____
2. A circular loop of wire, 12 cm in radius and of 0.05 resistance
lies in a uniform magnetic field which is normal to the plane of the
loop. At what rate must the magnetic field change to produce an induced
current of 0.2 A in the loop?
a. 2.2 T/s
b. 3.42 T/s
c. 4.76 T/s
d. 24.5 T/s
e. 88.5 T/s
Answer: _____
3. An airplane flies parallel to the Earth's surface at a point where
the downward component of the Earth's magnetic field is 0.4 x 10-4 T. If
the wingspan of the plane is 60 m and the induced potential between the
wingtips is 0.90 V, what is the plane's speed?
a. 250 m/s
b. 338 m/s
c. 375 m/s
d. 417 m/s
Answer: _____
4. What is the SI unit for the magnetic flux?
a. the gauss
b. the tesla
c. the weber
d. the Newton
Answer: _____
5. A circular loop of wire is placed perpendicular to a uniform
magnetic field of 0.50 T. External forces decrease the area of the loop
by 2.52 m2 in 2 seconds. Find the emf induced in the loop.
a. 0.23 V
b. 0.63 V
c. 1.26 V
d. 2.76 V
Answer: _____
6. A magnetic field is normal to the plane of a 0.15 x 0.30 rectangular
coil of 120 turns. The magnetic field is increased uniformly from 0.1 T
to 1.5 T. Find the time interval for the change if an emf induced in
the coil is 1.2 V.
a. 0.23 s
b. 2.6 s
c. 6.3 s
d. 9.6 s
Answer: _____
7. According to Lenz's law, the direction of an induced current in a
conductor will be that which tends to ______________.
a. enhance the effect which produces it
b. produce a greater magnetic field
c. produce the greatest emf
d. oppose the effect which produces it.
Answer: _____
8. A coil has 50 loops and a cross-sectional area of 0.25 m2. The coil
is spinning with an angular velocity of 4 rad/s in a magnetic field of
2 T. What is the maximum emf generated?
a. 100 V
b. 200 V
c. 400 V
d. 800 V
Answer: _____
9. A bar magnet is falling vertically through a horizontal loop of wire
with the south magnetic pole entering the loop first. What is the
direction of the induced current (viewed from above) as the south pole
enters the loop?
a. clockwise
b. counterclockwise
c. zero
Answer: _____
10. Suppose that a 15.0 cm x 5.00 cm plane rectangular loop of wire has
12 turns. A magnetic field of 2.50 T is normal to the plane of the
loop. This field is reduced to 1.00 T at a uniform rate in 3.00 ms.
What is the current induced in the loop if its total resistance is 2.00
?
a. 14.6 A
b. 18.2 A
c. 22.5 A
d. 27.9 A
Answer: _____
11. A circular coil of wire has a radius of 7 cm and contains 40 turns.
A field of 0.9 T passing through the coil collapses to zero in 0.2
seconds. What emf is generated in the wire?
a. 2.77 V
b. 3.26 V
c. 4.04 V
d. 4.27 V
Answer: _____