Question

20) The outer faces of a rectangular slab made of equal thickness of iron and brass are maintained at 100°C and
0°C respectively. The temperature at the interface is
(Thermal conductivity of iron and brass are 0.2 and 0.3 respectively.)
) 100°C
(2) 40°C
(3) 50°C
(4) 70°C​

Answer 1

Explanation:

Rate of flow of heat energy through iron=rate of flow of heat energy through brass

KA(dT)/l= KA(dT)/l

As Area and length are same, therfore,

0.2(100-T)=0.3(T-0)

20-0.2T=0.3T

T=20/0.5

T=40°C

Answer 2

Explanation:

Rate of flow of heat energy through iron=rate of flow of heat energy through brass

KA(dT)/l= KA(dT)/l

As Area and length are same, therfore,

0.2(100-T)=0.3(T-0)

20-0.2T=0.3T

T=20/0.5

T=40°C