Question

The three rods shown in figure (28-E7) have identical ifometrical dimensions. Heat flows from the hot end at a rate of 40W in the arrangement (a). Find the rates of heat flow when the rods are joined as in arrangement (b) and in (c). Thermal conductivities of aluminium and copper are 200W/m-°C and 400 W/m-°C respectively.

Answer 1

θ₁ – θ₂ = 100

Q/t = (θ₁ - θ₂)/R

R = R₁ + R₂ +R₃ = l/aK_Al + l/aK_Cu + l/aK_AL

R = R1 + R2 = R1 + (R_CuR_Al)/(R_Cu + R_Al)

For (c)