Assertion : Two bulbs of same wattage, one having a carbon filament and the other having a metallic filament are connected in series. Metallic bulbs will glow more brightly than carbon filament bulb.
Reason : Carbon is a semiconductor.

Options

A. If both assertion and reason are ture and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion and reason both are false.

Answer

D

Explanation

(d) When two bulbs are connected in series, the resistance of the circuit increases and so the voltage in each decreases. Due to decrease in temperature, the resistance of the carbon filament will slightly increase while that of metal filament will decrease. Hence, carbon filament bulb will glow more brightly `(P = i^(2) R)` Also carbon is not a semiconductor.