Question

Resistance of an incandescent filament of a bulb is comparatively much more than that when it is at room temperature. Why?

Answer 1

The resistance of the filament increases because when the bulb is switched on, the temperature of the filament increases.

• When the incandescent filament is connected to the circuit the temperature of the filament increases
• The  resistance of the wire is directly proportional to the length and temperature and inversly proportional to cross section of the wire
• when temperature of  a wire rises, the temperature of the filament also rises which increases its resistance