Question

A copper bar of length 1 m and cross-sectional area 10 × 10^-2 m² has its one end maintained at 100^oC by means of 0.4 kW electric heater. What is the temperature of the other end in steady state, given that the thermal conductivity of copper is 400 W/mK?

• (A) 60^oC
• (B) 70oC
• (C) 80oC
• (D) 90oC

Answer 1

The Correct Option is D

Explanation:
$\mathrm{As},\frac{dQ}{dt}=\frac{KA}{d}[T_H-T_C]$$\left[\frac{dQ}{dt}\right]\frac{d}{KA}=[T_H-T_C]\Rightarrow T_C=T_H-\left[\frac{dQ}{dt}\right]\frac{d}{KA}$$T_C=100-400\times \frac{1}{400\times 10\times {10}^{-2}}={90}^{\circ }\mathrm{C}$