Question

A thin metallic spherical shell of radius r carries a charge q on surface a point charge q is placed at the centre c and another 4 + to view is place outside the cell at a at a distance x from the centre

Answer 1

seems your question is incomplete. A complete question is ----> A thin metallic spherical shell of radius r carries a charge q on its surface. A point charge q/2 is placed at its centre C and on an other charge +2q is placed outside the shell at distance x from the centre.

Find (i) the force on the charge at the centre of shell and at the point A. (ii) the electric flux through the shell.

solution : (i) we know, electric field inside a spherical shell is zero. so, the force on the charge placed at the centre of shell is zero.

at the point A, the shell will behave as if the entire charge Qnet is placed at the centre of the shell. therefore, the total charge is Qnet = q + q/2 = 3q/2

since, its distance from 2q is x , so electric at point A is E = K(3q/2)/x² = 3Kq/2x²

so, electric force , F = (2q) × E = 3Kq²/x²

(ii) since, total charge enclosed by the shell is $Q_{en}=\frac{q}{2}$

so, electric flux through the shell , $\phi=\frac{Q_{en}}{\epsilon_0}=\frac{q}{2\epsilon_0}$