Question

A ring of radius r has given a charge Q and uniformly distributed over its length. If a charge qis placed at the centre. The electric potential energy of the charge q will be

kqQ/r^2

kqQ/r

-kq Q /r

Zero​

Answer 1

Answer:

Correct option is

C

8π

2

ε

0

R

2

Qq

Explanation:

T is tension in the ring.

Electrostatic force in radial direction will balance the tension component in that direction

2Tsinθ=

4πε

0

R

2

2πR

qQ(2θR)

angle θ is very small then sinθ=θ

2Tθ=

8π

2

ε

0

R

2

qQ2θ

T=

8π

2

ε

0

R

2

qQ