Two ends of area A of a uniform rod of thermal conductivity k are maintained at different but constant temperatures. At any point on the rod, the temperature gradient is `(dT)/(dl)`. If I be the thermal current in the rod, then:

Options

A. `I prop A`
B. `I prop (dT)/(dl)`
C. `I prop A^(@)`
D. `I prop(1)/(((dT)/(dl))`

Answer

A, B

Explanation

As the two ends of the rod are at constant temperature that means the rod is in steady state of thermal conduction and in steady state of thermal conduction the rate of heat flow (heat current) is given by the product of thermal conductivity, cross sectional area and the temperature gradient.