A charge Q is uniformly distributed over a large plastic plate. The electric field at point P, close to the centre of the plate is 10 Vm-1. If the plastic plate is replaced by a copper plate of the same dimensions and carrying same charge Q then the electric field at the point P will be

5 Vm-1 Zero 10 Vm-1 20 Vm-1

10 Vm-1

Because $E=\frac{\sigma}{\varepsilon_0}$