Alternating currents Quiz
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5 questions, one answer each
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1. An alternating supply has a period of 4.0 ms. What is its frequency?
- A. 250 Hz
- B. 25 Hz
- C. 0.25 Hz
- D. 4000 Hz
2. An alternating current has a peak value of 3.0 A. What is the r.m.s. current?
- A. 1.5 A
- B. 4.2 A
- C. 2.1 A
- D. 0.71 A
3. What does the r.m.s. value of an alternating p.d. represent?
- A. The peak p.d.
- B. The average p.d. over a cycle
- C. The steady p.d. that gives the same mean power
- D. Half the peak-to-peak p.d.
4. A 20 Ω resistor is connected to an a.c. supply of r.m.s. p.d. 10 V. What is the mean power?
- A. 5.0 W
- B. 0.50 W
- C. 200 W
- D. 10 W
5. A trace shows 2.5 divisions above the centre line at 4.0 V per division. What is the r.m.s. p.d.?
- A. 10 V
- B. 7.1 V
- C. 14 V
- D. 5.0 V