Question

A point charge $q$ is placed at the origin. How does the electric field due to the charge vary with the distance $r$ from the origin?

• A. The electric field varies inversely as the square of the distance from the point charge.
• B. The electric field varies directly as the square of the distance from the point charge.
• C. The electric field varies inversely as the cube of the distance from the point charge.
• D. The electric field varies directly as the cube of the distance from the point charge.

Answer 1

The correct option is A The electric field varies inversely as the square of the distance from the point charge.

Electric field due to a point charge $\left(q\right)$ is given by $E=\frac{1}{4\pi {\epsilon }_0}\frac{q}{r^2}$; where $r$ is the distance from the origin.

We can clearly see that $E\propto \frac{1}{r^2}$ i.e, it varies inversely as the square of distance from the point charge.