Question

A ring of uniform charge with radius 0.5 m having a 0.02 m gap, carries a charge +1C. The electric field at the centre is:

• A. $2.31\times {10}^{4}N/C$
• B. $2.31\times {10}^{8}N/C$
• C. $1.6\times {10}^{4}N/C$
• D. $1.6\times {10}^{8}N/C$

Answer 1

The correct option is B $2.31\times {10}^{8}N/C$

As gap is very-very small as compare to perimeter of the ring. So we can treat it as a point charge of charge, $q=\frac{1}{3.12}\times 0.02C$ and $F=\frac{1}{4\pi {\in }_0}\frac{q}{r^2}$