1. Which of the following is not an expression of power?

A. P = VI

B. P = I2R

C. P = V2/R

D. P = I/R

Answer d

Power is the product of voltage and current. Writing I in terms of V, we get

P = V^{2}/R

writing V in terms of I, we get

P = I^{2}r. [/bg_collapse]

2. Which of the following statements are true?

A. Power is proportional to voltage only

B. Power is proportional to current only

C. Power is neither proportional to voltage nor the current

D. Power is proportional to both the voltage and current

3. A 250V bulb passes a current of 0.3A. Calculate the power in the lamp.

A. 75W

B. 50W

C. 25W

D. 90W

4. Kilowatt-hour (kWh) is a unit of?

A. Current

B. Power

C. Energy

D. Resistance

5. Calculate the power in the 20 − ohm resistance.

A. 2000kW

B. 2kW

C. 200kW

D. 2W

6. A current of 5A flows in a resistor of 2 ohms. Calculate the energy dissipated in 300 seconds in the resistor.

A. 15kJ

B. 15000kJ

C. 1500J

D. 15J

7. Calculate the power across each 20 − ohm resistance.

A. 1000W, 1000W

B. 500W, 500W

C. 1000kW, 1000kW

D. 500kW, 500kW

8. Calculate the power across each 10 − ohm resistance.

A. 1000kW, 1000kW

B. 1kW, 1kW

C. 100W, 100W

D. 100kW, 100kW

9. Calculate the work done in a resistor of 20 ohms carrying 5A of current in 3 hours.

A. 1.5J

B. 15J

C. 1.5kWh

D. 15kWh

10. The SI unit of power is?

A. kW(kilowatt)

B. J/s(joules per seconD.

C. Ws(watt − seconD.

D. J/h(joules per hour