A charge of 1 µC 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 µC from infinity to the center of the circle? Let ke = 8.98 x 109 nm2/C2. Answer in units of J.
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.
dV/dx = -E
potential at the center of ring:
=> V = ...
With full calculations and explanations, the problem is solved.