Question

A charge $q$ is distributed uniformly on a ring of radius $r$ . A sphere of equal radius $r$ is constructed with its centre at the periphery of the ring. The electric flux through the surface of the sphere is

• A. $\frac{q}{\epsilon _{0}}$
• B. $\frac{2 q}{\epsilon _{0}}$
• C. $\frac{q}{2 \epsilon _{0}}$
• D. $\frac{q}{3 \epsilon _{0}}$

Answer 1

Answer: (D)

$Q \, =\frac{q_{e q}}{\epsilon _{0}}=\frac{q}{3 . \epsilon _{0}}$
If angle at centre is $360^\circ $ then charge is $q$
If angle at centre is $120^\circ $ then charge is $\frac{q}{360}\times 120$