Verified Solution • 2025–26 Session moderate

QNEET-2022-Ph-515: NEET 2022 Physics - Class 11 NEET-2022-Ph-515 Solution: Two rods one made of copper and other made of steel of same…

Two rods one made of copper and other made of steel of same length and same cross sectional area are joined together. The thermal conductivity of copper and steel are

385\ \text{J s}^{-1}\ \text{K}^{-1}\ \text{m}^{-1}

and

50\ \text{J s}^{-1}\ \text{K}^{-1}\ \text{m}^{-1}

respectively. The free ends of copper and steel are held at

100^\circ C

and

0^\circ C

respectively. The temperature at the junction is nearly:

88.5^\circ C

12^\circ C

50^\circ C

73^\circ C

Multiple Choice Options

A $88.5^\circ C$ 88. 5 _ C
B $12^\circ C$ 1 2 _ C
C $50^\circ C$ 5 0 _ C
D $73^\circ C$ 7 3 _ C

Step-by-Step Verified Solution

We know in conduction, rate of flow of heat q = _ K . A . _ T _ x As it is a case of steady state heat transfer _ _ K c u _ A _ [ 100 _ T j ] l = _ K s t e e l _ A _ [ T j _ 0 ] l Where T j is temperature of the junction _ 385 ( 100 _ T j ) = 50 ( T j ) _ 100 T j _ 1 = 50 385 _ 100 T j = 1 + 50 385 _ 100 T j = 1.1298 _ T j = 88.5 _ C

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