The coefficients of thermal conductivity of copper, mercury and glass are respectively `K_(c ), K_(m) and K_(g)` such that `K_(c ) gt K_(m) gt K_(g)`. If the same quantity of heat is to flow per second per unit area of each and corresponding temperature gradients are `X_(c ), X_(m) and X_(g)`

Options

A. `X_x=X_m=X_g`
B. `X_c gt X_m gt X_g`
C. `X_c lt X_m lt X_g`
D. `X_m lt X_c lt X_g`

Answer

C

Explanation

`(dQ//dt)/(A)=K((Deltatheta)/(Deltax))implies` Rate of flow of heat per unit area
= Thermal conductivity`xx`Temperature gradient
Temperature gradient `(X)prop(1)/("Thermal conductivity(K)")`
(As `(dQ//dt)/(A)=` constant)
As `K_C gt K_m gt K_G`, therefore `X_(c) lt X_(m) lt X_(g)`