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A torch bulb has a resistance of 1Omega ...

A torch bulb has a resistance of `1Omega` when cold. It draws a current of 0.2A from a source of 2V and glows. Calculate
(i) The resistance of the bulb when glowing and
(ii) Explain the reason for the different in resistance

Text Solution

Verified by Experts

(i) When the bulb glows :
(ii) V=IR------Ohm.s law R=V/I=2/.2=10`Omega`
(iii) 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.
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