For the situation described in figure, the magnetic field changes with time according to
`B=(2.00t^3-4.00t^2+0.8)t` and `r_2=2R=5.0cm`

(a) Calculate the force on an electron located at `P_2` at `t = 2.00 s`
(b) What are the magnitude and direction of the electric field at `P_1` when `t = 3.00 s` and `r_1= 0.02 m`.

Explanation

a. At `P_2`
`El=(dphi)/(dt)`
`E(2pir_2)=piR^2.(dB)/(dt)`
`:. E=R^2/(2r_2)((dB)/(dt))`