# Energy required to bring a charge of 61 ÂµC from infinity to the center of the circle

A charge of 1 ÂµC is distributed uniformly along the circumference of a circle with a radius of 30 cm. How much external energy is required to bring a charge of 61 ÂµC from infinity to the center of the circle? Let ke = 8.98 x 109 nm2/C2. Answer in units of J.

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#### Solution Preview

Because electric field at any point on axis of ring is given as:

E = ke *q*x/(r^2 + x^2)^(3/2)

where r is the radius of the ring and x is the distance of the point taken on axis of ring, from the center of the ring.

because,

dV/dx = -E

potential at the center of ring:

=> V = ...

#### Solution Summary

With full calculations and explanations, the problem is solved.

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