A heater joined in series with a ` 50 W` bulb is connected to the mains . If the `50 W` bulb is replaced by a `100 W` bulb , then will the heater now give more heat , less heat, or same heat ? Why ?

Explanation

Resistance of a bulb is given by `R = V^(2)//P`. Now, `100 W` bulb will haveless resistance. So we are connecting less resistance in series with the heater . It means potential difference across the heater will increase . So the heater will give more heat.