Chapter 8:
Magnetism and Its Uses
Practice Test
1.
How many turns are in the secondary coil of a step-down transformer that reduces a voltage from 900 V to 300 V and has 15 turns in the primary coil?
a.
3 turns
b.
5 turns
c.
60 turns
d.
30 turns
Hint
2.
How many turns are in the primary coil of a step-down transformer that reduces a voltage from 400 V to 100 V and has 80 turns in the secondary coil?
a.
20 turns
b.
320 turns
c.
160 turns
d.
40 turns
Hint
3.
What is the output voltage from a step-up transformer with 25 turns in the primary coil and 75 turns in the secondary coil if the input voltage was 120 V?
a.
60 V
b.
240 V
c.
360 V
d.
40 V
Hint
4.
A step-down transformer reduces voltage from 2400 V to 120 V. What is the ratio of the number of turns in the primary coil to the number of turns in the secondary coil of the transformer?
a.
20 / 1
b.
288,000 / 1
c.
2280 / 1
d.
1 / 20
Hint
5.
The coil of a 60 Hz generator makes 60 revolutions each second. How many revolutions does the coil make in 5 minutes?
a.
300 revolutions
b.
12 revolutions
c.
18,000 revolutions
d.
720 revolutions
Hint
6.
If a generator coil makes 6000 revolutions in 2 minutes, how many revolutions does it make each second?
a.
0.05 revolutions/s
b.
12,000 revolutions/s
c.
3000 revolutions/s
d.
50 revolutions/s
Hint
7.
What is the output voltage from a step-down transformer with 200 turns in the primary coil and 100 turns in the secondary coil if the input voltage was 750 V?
a.
375 V
b.
750 V
c.
1,500 V
d.
75 V
Hint
8.
The current produced by an AC generator switches direction twice for each revolution of the coil. How many times does a 110 Hz alternating current switch direction each second?
a.
440 times/s
b.
55 times/s
c.
880 times/s
d.
220 times/s
Hint
9.
How many turns are in the secondary coil of a step-up transformer that increases voltage from 30 V to 150 V and has 7 turns in the primary coil?
a.
35 turns
b.
30 turns
c.
150 turns
d.
1 turn
Hint
