Question

A torch bulb is rated $5V$ and $500mA$.

Calculate its a. power

Answer 1

Step 1- Given data and formulas

1. Applied voltage $V=5V$
2. Current through the bulb $I=500mA$

The electric power is given by,

$P=VI$

where $P$ is electric power.

Note: $1mA={10}^{-3}A$

Step 2- Finding the power

Substitute the known values into the formula.

$$\begin{gathered} P=5V\times 500\times {10}^{-3}A \\ P=2.5W \end{gathered}$$

Thus, the power of the bulb is 2.5 W.