Suppose the bent part of the frame of the previous problem has a thermal conductivity of 780 J s–1m–1 °C–1, whereas it is 390 J s–1m–1°C–1for the straight part. Calculate the ratio of the rate of hat flow through the bent part to the rate of heat flow through the straight part.

From previous question,–


w4.PNG


Now, its given bent part has k = 780 J s–1m–1 °C–1 and straight part has k =390 J s–1m–1°C–1for


Also Resistance equivalent circuit was as follows-


w5.PNG


Now,


RAB = , RBC = , RCD = RDE =, REF= and RBE =


After reducing the equivalent resistance across B and E, our circuit becomes


w5.PNG


Where


R1 = RBC+RCD + RDE


=


=


Since length is in cm and conductivity in meters, so multiply with 10-2


R1 =


Again, since R1 and RBE are in parallel, so total heat across R1 and RBE will be same.


ie, q1×R1 = q2 ×RBE


=


=


1