Identify the INCORRECT statement(s): (a) Electric field lines entering a Gaussian surface contribute negative flux. (b) A charge q is placed at the centre of a cube; the flux through every face is the same. (c) In a uniform electric field, the net flux through any closed Gaussian surface e

Question

Identify the INCORRECT statement(s): (a) Electric field lines entering a Gaussian surface contribute negative flux. (b) A charge q is placed at the centre of a cube; the flux through every face is the same. (c) In a uniform electric field, the net flux through any closed Gaussian surface enclosing no net charge is zero. (d) When the electric field is parallel to (tangent to) a Gaussian surface, it produces a finite non-zero flux through that surface. Choose the most appropriate option.

Accepted Answer

(d) only. (a) is correct: inward lines give negative flux. (b) is correct: by symmetry a charge at the cube's centre gives equal flux through each of the six faces. (c) is correct: with no enclosed charge, Gauss's law gives zero net flux regardless of the field. (d) is incorrect: if E is parallel to the surface, E. dA = 0, so the contribution is zero, not finite. Hence only (d) is the incorrect statement.

Solution

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