IIT JEE , AIEEE Forum - Physics , Electricity

joyfrancis

-E = dv / dr

-E_x = V_x / x

since the field is uniformly decreasing the potential at the origin would be 100V.

.: E_x = the electric field at x=+1 in the x dir.

= V_x / _x{change in potential divided by change in x co-ordinate}

=-20 / 1 = -20V/cm(i)

Now Ey = Vy / y

= -20 / y

now while using we only take the change i.e the positive change.

.: Enet = root (400 + something>=0) = Always greater than or equal to 20V/cm

It would be equal to 20V/m when there is zero displacement along the y direction.