Question

Find an expression for the heat transferred through a rectangular slab of area
of cross-section A, thickness d in time t. Its two faces are maintained at
temperatures Th and Tc (Th > Tc ) respectively. An electron and photon each have a wavelength 1.00 find the energy of photon and electron.

Answer 1

Thickness = d
Area of cross section = A
time = t
Let the conductivity = k
The two faces are at temperatures Th and Tc(Th>Tc).

So the heat flow rate is given as

$q=kA\ \frac{\Delta T}{d} \\ \\ \Rightarrow q=kA\ \frac{T_h-T_c}{d} \\ \\ \Rightarrow q= \frac{kA(T_h-T_c)}{d}\ W$

Heat transferred =Q

$Q = qt=\frac{kA(T_h-T_c)}{d} \times t=\frac{kAt(T_h-T_c)}{d}\ Joule$