Question

Why electric field strength in a sphere is zero?

Answer 1

The reason for zero electric fields inside the sphere

1. In a sphere when all the charges are on the surface, if we draw a Gaussian surface inside the sphere there will be no charge within the surface because of which the electric field lines emerging from the Gaussian surface are zero, so by Gauss theorem the electric field inside the hollow conducting sphere is also zero.
2. According to the gauss theorem, the electric flux through any surface is equal to the ratio of enclosed charge by the surface and the dielectric permittivity.

Mathematically

$\oint \overrightarrow{E}·d\overrightarrow{a}=\frac{q_{enclosed}}{{\epsilon }_o}$

$$\begin{gathered} \overrightarrow{E}=Electricfeildvector \\ \overrightarrow{a}=Areavector \\ {q}_{enclosed}=enclosedchargebythesurface \\ {\epsilon }_o=dielectricpermittivity \end{gathered}$$

Hence, the electric field inside the hollow conducting sphere is zero.