If s E · dS = 0 over a surface, then: (a) the magnitude of electric field on the surface is constant. (b) all the charges must necessarily be inside the surface. (c) the electric field inside the surface is necessarily uniform. (d) the number of flux lines entering the surface must be equal to the number of flux lines leaving it.

Answer: (d). E· dS = 0 means the net flux is zero, i.e. qenc = 0. It does not require E to be constant or uniform; charges may lie outside. Zero net flux means flux lines entering = flux lines leaving. So the answer is (d).

If s E · dS = 0 over a surface, then: | NEET 2023

Q57NEET 2023Easy

Electric Flux & Gauss's Law

If $\oint_s \vec{E} \cdot \overrightarrow{dS} = 0$ over a surface, then:

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Answer: (d)

$\oint \vec{E}\cdot d\vec{S} = 0$ means the net flux is zero, i.e. $q_{enc} = 0$ .
It does not require $E$ to be constant or uniform; charges may lie outside.
Zero net flux means flux lines entering = flux lines leaving.
So the answer is (d).

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