Which of the diagrams correctly represents the electric field between two charged plates if a neutral conductor is placed in between the plates?

The magnitude of electric field due to a point charge 2q, at distance r is E. Then the magnitude of electric field due to a uniformly charged thin spherical shell of radius R with total charge q at a distance $${r \over 2}(r > > R)$$ will be

A square sheet of side 'a' is lying parallel to XY plate at z = a. The electric field in the region is $$\overrightarrow E = c{z^2}\widehat k$$. The electric flux through the sheet is

Three charges q, $$-$$q and q₀ are placed as shown in figure. The magnitude of the net force on the charge q₀ at point O is $$\left[ {k = {1 \over {(4\pi { \in _0})}}} \right]$$