A non-conducting sheet of thickness d and large surface area contains a uniformly distributed charge of density $\rho$ throughout its volume. The electric field at a point P (deep inside the sheet far away from all corners) inside the sheet at a distance x from the central plane is $E_1$. Now the sheet is rolled to form a large solid cylinder. Field at a point P inside the cylinder at a distance x from its axis is  $E_2$. Find the ratio $\frac{E_1}{E_2}$