Sample 1Medium
A point charge q is placed exactly at the centre of an imaginary cube, which is drawn as a closed Gaussian surface with its six faces labelled. What is the electric flux through any one face?
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The answer is A.
By Gauss's law the total flux through the closed cube is q/ε₀. By symmetry it divides equally among the six faces, so each face has q/6ε₀.
- B.
q/ε₀ is the flux through the whole cube, not one face.
- C.
6q/ε₀ multiplies where it should divide.
- D.
Flux through a closed surface is zero only when it encloses no net charge, and here each face has outward flux.
NCERT: Class 12 Physics, Chapter 1