Question

A non-conducting ring of radius `0.5 m` carries a total charge of `1.11xx10^(-10)`C distributed non-uniformly on its circumference producing an electric field E everywhere is space. The value of the integral `int_(l=oo)^(l=0)-E.dI (l=0` being centre of the ring) in volt is
A. `+2`
B. `-1`
C. `-2`
D. zero

Answer 1

Correct Answer - A
`-int_(l=oo)^(l=0)E.dI=int_(l=oo)^(l=0) dV=V("centre")-V("infinity")`
but `V("infinity")=0`
`:.-int_(l=oo)^(l=0) E.dl` corresponds to potential at centre of ring
and `V("centre")=1/(4piepsilon_0).q/R=((9xx10^9)(1.11xx10^-10))/0.5~~2V`
Therefore the correct answer is a.