Q. A spherical shell of radius $R$ has a charge$+ q\ $units. The electric field due to the shell at a point
A) Inside is zero and varies as $r^{- 1}$ outside it
B) Inside the constant and varies as $r^{- 2}$ outside it
C) Inside is zero and varies as $r^{- 2}$ outside it
D) Inside is constant and varies as $r^{- 1}$ outside it
Explanation
(c) [image:1_image323.emf]
The electric field due to the spherical shell at point $+ P.$
$E = \frac{1}{4\pi\varepsilon_{0}}.\frac{q}{r^{2}}\ \ \ \ \ \ \ \ \ \ (\because r > R)$
$or\ \ \ E \propto \frac{1}{r^{2}}\ \ $
$or\ \ \ E \propto r^{- 2}$
According to Gauss’s law inside the shell electric field is zero.
$ie,\ \ \ \ \ \oint_{}^{}{\mathbf{E.ds} = 0}$
$or\ \ \ \ E = 0$
the electric field due to the shell at a point inside is zero and varies as $r^{- 2}$outside it.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.