Question

For a constant resistance, the correct relation between heat produced ($\text{H}$) and electric current ($\text{I}$) flowing is:

• A. $\text{H}\propto {\text{I}}^{-1}$
• B. $\text{H}\propto \text{I}$
• C. $\text{H}\propto {\text{I}}^2$
• D. $\text{H}\propto {\text{I}}^{-0.5}$

Answer 1

The correct option is C $\text{H}\propto {\text{I}}^2$

According to Joule's law, the heat produced in a resistor is;

1. directly proportional to the square of current for a given resistance.
2. directly proportional to resistance for a given current.
3. directly proportional to the time for which the current flows through the resistor.

$⟹\text{H}={\text{I}}^2\times \text{R}\times \text{t}$
Hence, $\text{H}\propto {\text{I}}^2$ is the right relation.