There is a horizontal cylindrical uniform but time-varying magnetic field increasing at a constant rate `dB//dt` as shown in Fig. 3.173. A charged particle having charge `q` and mass `m` is kept in equilibrium, at the top of a spring of spring constant `K`, in such a way that it is on the horizontal line passing through the center of the magnetic field as shown in the figure. The compression in the spring will be

Options

A. `1/K[mg-(qR^2)/(2l)(dB)/(dt)]`
B. `1/K[mg+(qR^2)/(l)(dB)/(dt)]`
C. `1/K[mg+(2qR^2)/(l)(dB)/(dt)]`
D. `1/K[mg+(qR^2)/(2l)(dB)/(dt)]`

Answer

D