Q69 / 90 · JEE Main 2021 (31 Aug Shift 2) · Physics

Choose the incorrect statement:
(a) The electric lines of force entering into a Gaussian surface provide negative flux.
(b) A charge q is placed at the centre of a cube. The flux through all the faces will be the same.
(c) In a uniform electric field net flux through a closed Gaussian surface containing no net charge, is zero.
(d) When an electric field is parallel to a Gaussian surface, it provides a finite non-zero flux.

Choose the most appropriate answer from the options given below:

  • A
    (b) and (d) Only
  • B
    (c) and (d) Only
  • C
    (a) and (c) Only
  • Correct answer
    D
    (d) Only

Solution

We know that electric flux is a scalar quantity and this is the scalar product of the magnitude of electric field and surface area. 

Figure

Recall, the formula given by Gauss theorem, ϕ=E→·A→=EAcosθ, here θ=90°, it means, ϕ=0.

Hence, the correct answer is option: 'D'.

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