Question

What does the lines of force at the region P and Q explain about?

Answer 1

The given figure shows the line of constant potential in a region in which an electric field is present. The values of potential is indicated in the figure.

Since, $E=\frac{dV}{dr}$. Therefore, the potential difference between any two consecutive lines is $dV=10V$. So, magnitude of electric field is $E=\frac{dV}{dr}$.

We can see that $E$ is maximum when distance between the lines is minimum. So, magnitude of electric field is greatest at $Q$, whereas at $P$ it is least.