Question

A small bulb has a resistance of 2 ohm when cold. It takes up a current of 0.4 ampere from a source of 4 volt and then starts to glow. Calculate
1. The resistance of the bulb when it starts glow.
2. Elaborate on the reason for the difference of resistance.

Answer 1

Answer:

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Explanation:

here you r answer

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Answer 2

Answer:

(i)given,

R' when cold= 2 ohm

I = 0.4 A

V= 4V

So,

V= IR

R= V/I

R= 4/0.4

R=10 - R'

R= 10-2

R= 8 ohm

(ii) Resistance of the filament of the bulb increases with increase in temperature. Hence when it glows its resistances is greater than when it is cold.

Hope it helps!!! :)