A conducting shell of radius R is placed with its centre at the origin as shown below. A point charge Q is placed inside the shell at a distance a along the x-axis from the centre.
The electric field at a distance b > R along the x-axis from the centre is
1
\(\frac{Q}{4 \pi \varepsilon_0 b^2} \hat{x} \)
2
\(\frac{Q}{4 \pi \varepsilon_0}\left[\frac{1}{(b-a)^2}-\frac{a R}{\left(a b-R^2\right)^2}\right] \hat{x} \)
3
\(\frac{Q}{4 \pi \varepsilon_0}\left[\frac{1}{(b-a)^2}+\frac{a R}{\left(a b-R^2\right)^2}\right] \hat{x} \)
4
\(\frac{Q}{4 \pi \varepsilon_0}\left[\frac{1}{b^2}-\frac{R^2}{a^2 b^2}\right] \hat{x} \)