Question

A current i passes through a wire of length l, radius of cross-section r and resistivity ρ. The rate of heat generation is

• A. $\frac{i^{2}l\rho}{\pi r^{2}}$
• B. $i^{2}\left( \frac{l\rho}{\pi r^{2}} \right)^{2}$
• C. $i^{2}l\rho ⥂ / ⥂ r$
• D. $il\rho ⥂ / ⥂ r$

Answer 1

Answer: (A)

$\frac{i^{2}l\rho}{\pi r^{2}}$

Answer 2

$H = i^{2}Rt$ ⇒ $\frac{H}{t} = i^{2}R = \frac{i^{2}\rho l}{\pi r^{2}}$