Temperature difference of 120 o C is maintained between two ends of a uniform rod A B of length 2 L .…

Temperature difference of 120oC is maintained between two ends of a uniform rod AB of length 2L. Another bent rod PQ, of same cross-section as AB and length 3L2, is connected across AB (See figure). In steady state, temperature difference between P and Q will be close to:

  1. 45oC
  2. 35oC
  3. 60oC
  4. 75oC

Solution

T1-T2=120oC

We define thermal resistance

R=LKA

Given circuit can be reduced to

Equivalent resistance Req=8R5

Thermal current i=T1-T28R5

TP-TQ=T1-T28R5 3R5

=38×120=45

Asked in: JEE Main 2019 (09 Jan Shift 1)

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