Question

A ring shaped conductor with radius a carries a net positive charge `q` uniformly distributed on it as shown in figure. `A` point `P` is situated at a distance `x` from its centre. Which of following graph shows the correct variation of electric field `(E)` wilth distance `(x)`?

A.
B.
C.
D. None of these

Answer 1

(c) The net electric field at point `P` is given by
`E=(qx)/(4pi epsilon_(0)(x^(2)+a^(2))^(3//2)hati`
`:.` At the centre of ring `x=0=0E_(0)`
If `x gt gt a, E=1/(4pi epsilon_(0))q/(x^(2))`

and `E` will be maximum where,
`(dE)/(dx)=0` or `x=+-a/(sqrt(2))`
and `E_("max")=1/(4piepsilon_(0)(2q)/(3sqrt(3)a^(2))`