Question

The brightness of light, emitted by a bulb, is observed to decrease when an
electric heater is connected in series with it. Suggest the likely reason for this
observation.
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Answer 1

Explanation:

The voltage is divided into two parts so the available voltage for the bulb is less than 220 V. So, the brightness of light emitted from the bulb will decrease. The reason for this is that heater demands higher voltage so some of the voltage will be cut off from the bulb in order to provide full current to the heater because heater needs more current to work as compared to the bulb.

Answer 2

When the heater is connected in series with the bulb, it will reduce the current flowing through the bulb. This reduces the brightness of the bulb.