Question

A small circular ring has a uniform charge distribution. On a far-off axial point at a distance $x$ from the centre of the ring, the electric field is proportional to -

• A. $x^{-1}$
• B. $x^{-3/2}$
• C. $x^{-2}$
• D. $x^{-5/4}$

Answer 1

The correct option is C $x^{-2}$

At the far point from the small uniformly charged circular ring on the axis, the ring behaves as a point charge.

$\therefore E=\frac{kq}{x^2}$

$\Rightarrow E\propto x^{-2}$