A semicircular rods is joined at its end to a straight rod of the same material and the same cross-sectional area. The straight rod forms a diameter of the other rod. The junctions are maintained at different temperatures. Find the ratio of the heat transferred through a cross section of the straight rod in a given time.

Answer

B

Explanation

We know `Q=(kA(theta_1-theta_2))/(d)`
`Q_1=(kA(theta_1-theta_2))/(D_1)`
`Q_2=(kA(theta_1-theta_2))/(d_2)`
`(Q_1)/(Q_2)=(KA(theta_1- theta_2))/((pi r)/((KA(theta_1-theta_2))/(2 r)))=(2R)/(pir)=2/(pi)`
where `d_1=(pi)e, d_2=2r.`