Question

Two electric bulbs rated $P_1$ watt V volts and $P_2$ watt V volts are connected in parallel and applied across V volts. The total power (in watts) will be :

• A. $P_1+P_2$
• B. $\sqrt{P_1{P}_2}$
• C. $\frac{P_1{P}_2}{P_1+P_2}$
• D. $\frac{P_1+P_2}{P_1{P}_2}$

Answer 1

The correct option is A $P_1+P_2$

Let resistances be $R_1$ and $R_2$

Then,

$P_1=\frac{V^2}{R_1}$

$P_2=\frac{V^2}{R_2}$ ...(1)

In parallel, we get: $R_{eq}=\frac{R_1{R}_2}{R_1+R_2}$ ..(2)

Again, replacing values of $R_1$ and $R_2$ using (1),

We get: $P=P_1+P_2$