Question

The ends of an element of zinc wire are kept at a small temperature difference $\Delta T$ and a small current $\left(I\right)$ is passed through the wire. Then, the heat developed per unit time :

• A. is proportional to $\Delta T$ and $I$
• B. is proportional to $I^3$ and $\Delta T$
• C. is proportional to Thomson cefficient of the metal
• D. is proportional to $\Delta T$ only

Answer 1

The correct option is A is proportional to $\Delta T$ and $I$

The voltage developed across the wire will be proportional to $\Delta T$. Power flowing through it is $VI$ which is proportional to $I\Delta T$ and hence heat developed will be proportional to $\Delta T$ and $I$.