We have a non$-$conducting cylinder of radius $40$ cm one meter long with a hole of radius $20$ cm in its center.

A hole of $20$ cm radius has been drilled in its center. The cylinder has a charge density of$\mathrm{ 5}\mu$C$/$m$3$

Calculate the electric field for the following regions:

$($a$)$ r $=8\mathrm{.}2$ cm$.$

$($b$)$ r $=30$ cm$.$

$($c$)$ r $>40$ cm$.$