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.
Ain both cases power lost is same but temperature of rod is more in case- $1$
Bin case- $1$ power lost as well as temperature of rod is more
Cin case- $2$ power lost as well as temperature of rod is more
Din case- $1$ power lost is more but temperature of rod is less
Medium
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Bin 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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