Question

Two rods with the same dimensions have thermal conductivities in the ratio 1 : 2. they are arranged between heat reservoirs with the same temperature difference, in two different configurations, A and B. The rates of heat flow in A and B are `I_(A) and I_(B)` respectively. The ratio `(I_(A))/I_(B))` is equal to

A. `1 : 2`
B. `1 : 3`
C. `2 : 5`
D. `2 : 9`

Answer 1

Correct Answer - D
Rate of heat flow `lalpha(TD)/R`
(H = Temperature difference between two points//R)
As TD = temperature difference is same.
`therefore` I `alpha (1)`/(Thermal resistance)
`I_(A)/I_(B)=R_(B)/R_(A)` = ((R)(2R)//R+2R)/(R+2R) = 2/9`