Discussion
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- Question
A given power supply is capable of providing 6 A for 3.5 h. Its ampere-hour rating is
Options- A. 0.58 Ah
- B. 2.1 Ah
- C. 21 Ah
- D. 58 Ah
- Correct Answer
- 21 Ah
- 1. A 3.3 kΩ resistor dissipates 0.25 W. The current is
Options- A. 8.7 mA
- B. 87 mA
- C. 8.7 µA
- D. 8.7 A Discuss
- 2. 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
- 3. 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
- 4. 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
- 5. 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
- 6. At the end of a 14 day period, your utility bill shows that you have used 18 kWh. What is your average daily power?
Options- A. 1.286 kWh
- B. 12.85 kWh
- C. 535 kWh
- D. 252 kWh Discuss
- 7. Three hundred joules of energy are consumed in 15 s. The power is
Options- A. 2,000 W
- B. 2 W
- C. 20 W
- D. 200 W Discuss
- 8. For 12 V and 40 mA, the power is
Options- A. 480 mW
- B. 0.480 W
- C. 480,000 µW
- D. all of the above Discuss
- 9. When the pointer of an analog ohmmeter reads close to zero, the resistor being measured is
Options- A. overheated
- B. shorted
- C. open
- D. reversed Discuss
- 10. If it takes 400 ms to use 12,000 J of energy, the power is
Options- A. 30 kW
- B. 30 W
- C. 3 W
- D. 300 kW Discuss
Energy and Power problems
Search Results
Correct Answer: 8.7 mA
Explanation:
W = I2R
I = square root(W/R)
= square root( 0.25/(3.3x1000) )
= 0.0087038828
= 8.7 mA
I = square root(W/R)
= square root( 0.25/(3.3x1000) )
= 0.0087038828
= 8.7 mA
Correct Answer: 132 mW
Correct Answer: 150 mW
Correct Answer: 0.938 Wh
Correct Answer: 1,170 Wh
Correct Answer: 1.286 kWh
Correct Answer: 20 W
Correct Answer: all of the above
Correct Answer: shorted
Correct Answer: 30 kW
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