Transformers Quiz
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5 questions, one answer each
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1. A transformer has 500 turns on the primary and 50 turns on the secondary. The primary p.d. is 230 V. What is the secondary p.d. if it is ideal?
- A. 2300 V
- B. 23 V
- C. 46 V
- D. 0.23 V
2. What is the main reason a transformer core is laminated?
- A. To increase the magnetic flux
- B. To reduce eddy currents
- C. To reduce the resistance of the windings
- D. To stop flux leakage
3. A transformer has an input of 200 W and an output of 190 W. What is its efficiency?
- A. 5%
- B. 10.5%
- C. 95%
- D. 105%
4. A 2.0 MW supply is sent at 100 kV along lines of resistance 10 Ω. What is the power lost in the lines?
- A. 4.0 kW
- B. 2.0 kW
- C. 200 kW
- D. 40 kW
5. Transmission voltage is raised from 25 kV to 250 kV for the same power. By what factor does the power loss in the lines change?
- A. It falls by a factor of 10
- B. It rises by a factor of 10
- C. It falls by a factor of 100
- D. It is unchanged