Eduprobe
Question:
A cubical region of side a has its centre at the origin. It encloses three fixed point charges, -q at (0, -a/4, 0), +3q at (0, 0, 0) and -q at (0, +a/4 ,0). Choose the correct option(s):
The net electric flux crossing the plane x = +a/2 is equal to the net electric flux crossing the plane x = -a/2
The net electric crossing the plane y = +a/2 is more than the net electric flux crossing the plane y = -a/2
The net electric flux crossing the entire region is q/ε₀
The net electric flux crossing the plane z = +a/2 is equal to the net electric flux crossing the plane x = +a/2
The net electric flux crossing the plane x = +a/2 is equal to the net electric flux crossing the plane x = -a/2
The net electric crossing the plane y = +a/2 is more than the net electric flux crossing the plane y = -a/2
The net electric flux crossing the entire region is q/ε₀
The net electric flux crossing the plane z = +a/2 is equal to the net electric flux crossing the plane x = +a/2
Solution:
Net flux through cube = -q + 3q - q/ε₀ = q/ε₀
Due to symmetry, the flux passing through x = -a/2, y = a/2 and z = a/2 is the same.