Question

An electric bulb of rating $\text{50 W}$ is used for $\text{8 hours}$ a day. The number of units of energy used by the electric bulb in a day is:

• A. 0.2 units
• B. 0.4 units
• C. 0.6 units
• D. 0.8 units

Answer 1

The correct option is B

0.4 units

Given, power of the bulb, $P=50W=0.05kW$ and

Time, $t=8hours$

$Power=\frac{EnergyorWork}{Time}$

So, $\text{E}nergy=\text{Power}\times \text{Time}$
$=0.05\times 8$ $=0.4kWh$
$=0.4\text{u}nits$ (Since, $1kWh=1unit$).