Page 62 - Teach Yourself Electricity and Electronics
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42 Electrical units
C. The foot pound.
D. The kilowatt hour.
12. The frequency of common household ac in the U.S. is:
A. 60 Hz.
B. 120 Hz.
C. 50 Hz.
D. 100 Hz.
13. Half-wave rectification means that:
A. Half of the ac wave is inverted.
B. Half of the ac wave is chopped off.
C. The whole wave is inverted.
D. The effective value is half the peak value.
14. In the output of a half-wave rectifier:
A. Half of the wave is inverted.
B. The effective value is less than that of the original ac wave.
C. The effective value is the same as that of the original ac wave.
D. The effective value is more than that of the original ac wave.
15. In the output of a full-wave rectifier:
A. The whole wave is inverted.
B. The effective value is less than that of the original ac wave.
C. The effective value is the same as that of the original ac wave.
D. The effective value is more than that of the original ac wave.
16. A low voltage, such as 12 V:
A. Is never dangerous.
B. Is always dangerous.
C. Is dangerous if it is ac, but not if it is dc.
D. Can be dangerous under certain conditions.
17. Which of these can represent magnetomotive force?
A. The volt-turn.
B. The ampere-turn.
C. The gauss.
D. The gauss-turn.
18. Which of the following units can represent magnetic flux density?
A. The volt-turn.
B. The ampere-turn.
