Question

If you run a 500 W computer for 4 hours, your electric meter will read ____; this is a measure of _______ “used”

A) 2000 kWh, energy
B) 2000 kWh, power
C) 2 kWh, current
D) 2 kWh, energy
E) 2 kWh, voltage
F) 2000 kWh, current
G) 2000 kWh, voltage
H) 2 kWh, power

1. diemkieu

D) 2 kWh, energy

Explanation:

Energy = power×time

For electricity,

E = Pt……………….. Equation 1

Where E = Electric Energy, P = power, t = time.

Given: P = 500 W, t = 4 hours.

Substitute into equation 1

E = 500(4)

E = 2000 Wh

E = (2000/1000) kWh

E = 2 kWh.

Hence the right option is D) 2 kWh, energy

2. quangkhai

If you run a 500 W computer for 4 hours, your electric meter will read 2kWh; this is a measure of energy “used”. The correct answer is D.

Explanation: Energy is defined as the capacity of doing work and is occurs in different forms( electrical, kinetic, potential energy). Electrical energy consumption can be calculated or measure through the multiplication of the power( W or kW) used by the number of hours during which the power is consumed. Therefore the unit of energy is kWh. From the question,

500W was used for 4 H

Therefore energy consumed

500× 4= 2000Wh. To convert to kWh

Divide by 1000,

2000÷ 1000= 2.

There energy consumed in kWh is,

2kWh energy.