1)

Consider a pair of insulating blocks with thermal resistances R1 and R2 as shown in the figure. The temperature θ at the boundary between the two blocks is

632021414_lugyivztrc6x-q.png


A) θ1θ2R1R2(θ1+θ2)(R1+R2)

B) θ1R1+θ2R2(R1+R2)

C) [(θ1+θ2)R1R2](R21+R22)

D) (θ1R2+θ2R1)R1+R2

Answer:

Option D

Explanation:

Rate of transmission of heat

=TemperaturedifferenceThermalresistance

dQdt=dθR

Here, dQdt

= θθ2R2=θ1θR1

= R1θR1θ2 = R2θ1R2θ

θ = (R2θ1+R1θ2)R1+R2