Question
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.
✓
Answer
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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