Question

How much electricity is used by a 100-watt light bulb in 20 seconds? a) 0.002 kWh

b) 0.05 kWh
c) 0.2 kWh
d) 2 kWh

Answer 1

The amount of electricity used by a 100-watt light bulb in 20 seconds is 0.002 kWh.

Step-by-step explanation:

To find the amount of electricity used by a 100-watt light bulb in 20 seconds, we need to calculate the energy consumed. Energy is given by the formula:

Energy = Power x Time

In this case, the power is 100 watts and the time is 20 seconds. Substituting these values into the formula:

Energy = 100 watts x 20 seconds = 2000 joules

Since the question provides answer options in kilowatt-hours (kWh), we need to convert joules to kWh. 1 kWh = 3.6x10^6 joules. Therefore:

Energy = 2000 joules / (3.6x10^6 joules/kWh) = 0.00055 kWh

Rounding to the nearest thousandth, the correct answer option is a) 0.002 kWh.