# Math Help - Dielectric sheet - Find speed with which electron crosses sheet?

1. ## Dielectric sheet - Find speed with which electron crosses sheet?

An infinite dielectric sheet having charge density $\sigma$ has a hole of radius $R$ in it. An electron is released on the axis of the hole at a distance $\sqrt{3}R$ from the centre. Find the speed with which it crosses the plane of the sheet.

$v = \sqrt{\frac{\sigma eR}{m\epsilon_0}}$