The wall of a house is made of two different materials of same thickness. The temperatures of the outer wall is `T_(2)` and that of inner wall is `T_(1) lt T_(2)`. The temperature variation inside the wall as shown in the figure. Then :

Options

A. thermal conductivity of inner wall is greater than that of outer
B. thermal conductivity of outer wall is greater than that of inner
C. thermal conductivities of the two equal
D. no conclusion can be drawn about thermal conductivities

Answer

B

Explanation

The slope of temperature variation is more in inner
`(dQ)/(dt)=(KA)/(l).DeltaT`
`Delta T=(l)/(KA).(dQ)/(dt)`
Slope `alpha (1)/(K)`
Larger the conductivity, smaller is the slope.