Electric Charges and Fields — Physics STD 12 Science — Question
Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsElectric Charges and Fields1 Mark
Question
If $\int_\text{S}\text{E.dS}=0$ over a surface, then:
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Answer
The number of flux lines entering the surface must be equal to the number of flux lines leaving it.
All charges must necessarily be outside the surface.
Given,
$\int_\text{s}\text{E.dS}=0$
It means the algebraic sum of number of flux lines entering the surface and number of flux lines leaving the surface.
Now, from Gauss' law,
$\int_\text{S}\text{E.dS}=\frac{\text{q}}{\epsilon_0}$
Where qis charge enclosed by the surface.
Now,
$\int_\text{s}\text{E.dS}=0$
q = 0 i.e.,net charge enclosed by the surface must be zero.
Hence, all other charges must necessarily be outside the surface.
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