A circular disc of radius carries surface charge density

PHYSICS · Subjective · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields

Problem

A circular disc of radius

R

carries surface charge density

\sigma(r) = \sigma_0 \left(1 - \frac{r}{R}\right)

, where

\sigma_0

is a constant and

r

is the distance from the center of the disc. Electric flux through a large spherical surface that encloses the charged disc completely is

\phi_0

. Electric flux through another spherical surface of radius

\frac{R}{4}

and concentric with the disc is

\phi

. Then the ratio

\frac{\phi_0}{\phi}

is _____. [Adv. 2020]