Q. According to Joule’s law, if the potential difference across a conductor having a material of specific resistance remains constant, then the heat produced in the conductor is directly proportional to
A) $\rho$
B) $\rho^{2}$
C) $\frac{1}{\sqrt{\rho}}$
D) $\frac{1}{\rho}$
Explanation
(d) $P = \frac{V^{2}}{R}\ $but$\ R = \frac{\rho l}{A} \Rightarrow P = \frac{V^{2}}{\rho l\ /\ A} = \frac{AV^{2}}{\rho l}$. Since $\frac{AV^{2}}{l}\ $is constant as per given condition so$\ P \propto \frac{1}{\rho}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.