Energy and Power problems
- 1. If you used 600 W of power for 60 h, you have used
Options- A. 36 kWh
- B. 3.6 kWh
- C. 10 kWh
- D. 1 kWh Discuss
Correct Answer: 36 kWh
- 2. If you used 400 W of power for 30 h, you have used
Options- A. 1.3 kWh
- B. 13.3 kWh
- C. 1.2 kWh
- D. 12 kWh Discuss
Correct Answer: 12 kWh
- 3. A 220 Ω resistor dissipates 3 W. The voltage is
Options- A. 73.3 V
- B. 2.5 V
- C. 25.7 V
- D. 257 V Discuss
Correct Answer: 25.7 V
- 4. A power supply produces a 0.6 W output with an input of 0.7 W. Its percentage of efficiency is
Options- A. 8.57%
- B. 42.85%
- C. 4.28%
- D. 85.7% Discuss
Correct Answer: 85.7%
- 5. A 75 Ω load uses 2 W of power. The output voltage of the power supply is approximately
Options- A. 120 V
- B. 1.2 V
- C. 12 V
- D. 6 V Discuss
Correct Answer: 12 V
- 6. In 0.025 W, there are
Options- A. 25 kW
- B. 0.00025 mW
- C. 2,500 µW
- D. 25 mW Discuss
Correct Answer: 25 mW
- 7. How many watt-hours represent 65 W used for 18 h?
Options- A. 11.7 Wh
- B. 1,170 Wh
- C. 11,700 Wh
- D. 117,000 Wh Discuss
Correct Answer: 1,170 Wh
- 8. A 15 V source is connected across a 12 Ω resistor. How much energy is used in three minutes?
Options- A. 938 Wh
- B. 0.938 Wh
- C. 56.25 Wh
- D. 5.6 Wh Discuss
Correct Answer: 0.938 Wh
- 9. A 120 Ω resistor must carry a maximum current of 25 mA. Its rating should be at least
Options- A. 4.8 W
- B. 150 mW
- C. 15 mW
- D. 480 mW Discuss
Correct Answer: 150 mW
- 10. A 68 Ω resistor is connected across the terminals of a 3 V battery. The power dissipation of the resistor is
Options- A. 132 mW
- B. 13.2 mW
- C. 22.6 mW
- D. 226 mW Discuss
Correct Answer: 132 mW
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