Question

If an electric bulb of 100 watt is lighted for 2 hours, how much electric energy would be consumed?

Answer 1

Step 1: Given data

Power of electric bulb is, $P=100W$

Time for which the bulb is lighted is, $t=2h=2\times 3600s=7200s$

Step 2: Calculating energy

Power is given as,

$P=\frac{E}{t}$

where, $E$ is energy and $t$ is time.

Substituting the known values in the equation for power, we get,

$$\begin{gathered} 100W=\frac{E}{7200s} \\ E=100\times 7200 \\ E=7.2\times {10}^{5}J \end{gathered}$$

Therefore, the electrical energy consumed by the bulb is $7.2\times {10}^{5}J$.