JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Electrostatics

In a cuboid of dimension

2 L \times 2 L \times L

, a charge q is placed at the centre of the surface '

S

' having area of

4 L^{2}

. The flux through the opposite surface to ' S ' is given by

Answer: (D)

Solution

The charge sits at the centre of the

2 L \times 2 L

face

S

. Reflecting the cuboid about that face completes a cube of side

2 L

with the charge at its centre. By symmetry the flux is shared equally among the six faces of this cube, each receiving

\frac{q}{6 ε _{0}}

. The face of the original cuboid opposite to

S

is exactly one face of this cube, so the flux through it is

\frac{q}{6 ε _{0}}

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Single correct option