Question

Two identical rings `P and Q` of radius `0.1 m` are mounted coaxially at a distance `0.5 m` apart. The charges on the two rings are `2 mu C and 4 mu C`, respectively. The work done in transferring a charge of `5 mu C` from the center of P to that of Q is.
A. 1.28 J
B. 0.72 J
C. 0.144 J
D. 2.24 J

Answer 1

Correct Answer - b
`V_1 = ( k xx 2 xx 10^-6)/(0.1) + (k xx 4 xx 10^-6)/(sqrt((0.1)^2 + (0.5)^2)`
`V_2 = (k xx 4 xx 10^-6)/(0.1) + (k xx 2 xx 10^-6)/(sqrt((0.1)^2 + (0.5)^2)`
Work done is `q(V_2 - V_1) = 0.72 J`.