Question

Two rods P and Q of same length and same diameter having thermal conductivity ratio2 : 3 joined end to end. If temperature at one end of P is 100ºC and at one end of Q 0ºC, then the temperature of the interface is –

• A. 40⁰C
• B. 50⁰C
• C. 60⁰C
• D. 70⁰C

Answer 1

Answer: (A)

40⁰C

Answer 2

$\frac{K_{p}A\lbrack 100–\theta\rbrack}{\mathcal{l}}$ = $\frac{K_{Q}.A\lbrack\theta\rbrack}{\mathcal{l}}$

\ $\frac{K_{p}}{K_{Q}}$ = $\frac{2}{3}$ = $\frac{\theta}{100–\theta}$ OR (q = 40⁰C)