Question

P is a point on the axis of a ring with Centre 0 and radius 0.1m. The ring is uniformly charged with linear charge density 0.5 c/m. Given OP = 0.1 m, the electric field at P is approximately ten to the power ____ in SI units.

___

Answer 1

The electric field due to a uniformly charged ring at a point on the axis is given by $E=\frac{KQx}{(R^2+x^2{)}^{\frac{3}{2}}}$ where x is the distance of the point from the Centre and R is the radius of the ring

Again it’s not required to remember this formula. In fact one must try to not mug up formulas. To be convinced with this I recommend you to re-watch the derivation video.

Here $Q=\lambda \ast 2\pi R=0.5\ast 2\ast \pi \ast 0.1=0.314C$

Here on plugging the values of, $(K=9\ast {10}^9),(Q=0.314C)(x=0.1m)and(R=0.1)$,We get $E\approx {10}^{11}\frac{N}{C}$