If a point charge is placed at the centre of the cube, then flux linked to the surface shaded in figure is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → \( \frac{Q}{2\varepsilon_0} \)
By Gauss's law, the total flux through the closed surface of the cube is \( Q/\varepsilon_0 \). With the charge at the centre, the six faces are placed symmetrically, so each face carries one-sixth of it.
\( \displaystyle \Phi_{\text{face}} = \frac{Q}{6\varepsilon_0} \)
The figure shows three shaded faces, so
\( \displaystyle \Phi = 3 \times \frac{Q}{6\varepsilon_0} = \frac{Q}{2\varepsilon_0} \)