Question

The wattage of a bulb is 24 W when it is connected to a 12 V battery. Calculate its effective wattage if it operates on a 6 V battery.

Answer 1

We know that the power (P) is given by,

$P=\frac{V^2}{R}$

where V = Voltage rating and

R = Resistance of the element

$P=\frac{{\left(12\right)}^2}{R}$

$R=\frac{{12}^2}{\left(24\right)}=6Ohm$

Now if we use 6 Volt for the same bulb then the power is given by,

$P=\frac{V^2}{R}=\frac{6^2}{6}=6Watt$