A charge q is located above the centre of a square plate of side a, at a distance a2. The flux of electric field through the plate Is?
q/6ε0
Consider five more faces such that it forms a closed cube with ‘q’ at its centre.
Flux through this cube =qϵ0
By symmetry, as the charge is symmetrically located.
ϕone face=q6ϵ0=16 Total flux
Hence (d).