Why do electric field lines not form closed loop ?

A charge $Q$ is fixed at a distance $d$ in front of an infinite metal plate. The lines of force are represented by

How field lines depend on area or on solid angle made by area ?

Draw electric field lines of positive charge.

Draw electric field by negative charge.

A charge $+q$ is placed somewhere inside the cavity of a thick conducting spherical shell of inner radius $R_1$ and outer radius $R_2$. A charge $+Q$ is placed at a distance $r > R_2$ from the centre of the shell. Then the electric field in the hollow cavity