2–25 consider a medium in which the heat conduction equation is given in its simplest form as
d^2t/dx^2 + d^2t/dy^2 = 1/a dt/dt
(a) is heat transfer steady or transient?
(b) is heat transfer one-, two-, or three-dimensional?
(c) is there heat generation in the medium?
(d) is the thermal conductivity of the medium constant or variable?

d) Is the thermal conductivity of the medium constant or variable.

Explanation:

As we know that

Heat equation with heat generation at unsteady state and with constant thermal conductivity given as

With out heat generation

In 2 -D with out heat generation with constant thermal conductivity

Given equation

So we can say that this is the case of  with out heat generation ,unsteady state and with constant thermal conductivity.

So the option d is correct.

d) Is the thermal conductivity of the medium constant or variable.