Question

If K 1 and K 2 are the thermal conductivities, L 1 and L 2 are the lengths and A 1 and A 2 are the cross sectional areas of steel and copper rods respectively such that $\frac{K_2}{K_1}=9,\frac{A_1}{A_2}=2,\frac{L_1}{L_2}=2.$

Then, for the arrangement as shown in the figure, the value of temperature T of the steel-copper junction in the steady state will be

• A. 18°C
• B. 14°C
• C. 45°C
• D. 150°C

Answer 1

Answer: (C)

45°C

Answer 2

The correct option is(C): 45°C

$450-T=\frac{dQ}{dt}×\frac{l_1}{K_1A_1}$

$450-T=9T$

$⇒T=45°C$