Question

One end of a conducting rod is maintained at temperature ${50}^{\circ }C$ and at the other end ice is melting at $0^{\circ }C$. The rate of melting of ice is doubled if

• A. the temperature is made ${200}^{\circ }C$ and the area of cross-section of the rod is doubled.
• B. the temperature is made ${100}^{\circ }C$ and length of rod is made four times.
• C. area of cross-section of rod is halved and length is doubled.
• D. the temperature is made ${100}^{\circ }C$ and the area of cross-section of rod and length both are doubled.

Answer 1

Answer: (D)

the temperature is made ${100}^{\circ }C$ and the area of cross-section of rod and length both are doubled.

Rate of heat transfer $Q=KA\frac{\Delta T}{l}$
Initially.
$Q=KA\frac{50}{l}$
option (a): $Q_2=8Q$

option (b): $Q_2=Q/2$

option (c): $Q_2=Q/4$

option (d): $Q_2=Q$