A constant potential difference is applied to the ends of a graph… - Vidyadip

MCQ

A constant potential difference is applied to the ends of a graphite rod, whose resistance decreases with a rise of temperature. The rod can be $(1)$ covered with asbestos or $(2)$ left open to atmosphere. Answer for steady state.

A
in both cases power lost is same but temperature of rod is more in case- $1$
✓
in case- $1$ power lost as well as temperature of rod is more
C
in case- $2$ power lost as well as temperature of rod is more
D
in case- $1$ power lost is more but temperature of rod is less

✓

Answer

Correct option: B.

in case- $1$ power lost as well as temperature of rod is more

b
In steady state, as asbestos is a poor conductor of heat than air, temperature of rod $( 1 )$ will be higher.

Also as temperature of rod $(1)$ is high

$\Rightarrow r \downarrow \Rightarrow \frac{v^{2}}{r} \uparrow$

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