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प्रश्न
If `oint_s` E.dS = 0 over a surface, then ______.
- the electric field inside the surface and on it is zero.
- the electric field inside the surface is necessarily uniform.
- 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.
पर्याय
a and b
b and c
c and d
a and d
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उत्तर
c and d
Explanation:
We know electric flux is proportional to the number of electric field lines and the term `oint_s` E.dS represents electric flux over the closed surface.
It means `oint_s` E.dS represents the algebraic sum of the number of flux lines entering the surface and number of flux lines leaving the surface.
If `oint_s` E.dS = 0, this means the number of flux lines entering the surface must be equal to the number of flux lines leaving it.
From Gauss’ law, we know `oint_sE.dS = q/ϵ_0`, here q is the charge enclosed by , the closed surface. If `oint_sE.dS` = 0 then q = 0, i.e., net charge enclosed by the surface must be zero.
Hence all other charges must necessarily be outside the surface. This is because of the fact that charges outside the surface do not contribute to the electric flux.
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संबंधित प्रश्न
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The surface considered for Gauss’s law is called ______.
The Electric flux through the surface
 (i) |
 (ii) |
 (iii) |
 (iv) |
If there were only one type of charge in the universe, then ______.
- `oint_s` E.dS ≠ 0 on any surface.
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- `oint_s` E.dS could not be defined.
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Consider a region inside which there are various types of charges but the total charge is zero. At points outside the region
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Refer to the arrangement of charges in figure and a Gaussian surface of radius R with Q at the centre. Then
- total flux through the surface of the sphere is `(-Q)/ε_0`.
- field on the surface of the sphere is `(-Q)/(4 piε_0 R^2)`.
- flux through the surface of sphere due to 5Q is zero.
- field on the surface of sphere due to –2Q is same everywhere.
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In finding the electric field using Gauss law the formula `|vec"E"| = "q"_"enc"/(epsilon_0|"A"|)` is applicable. In the formula ε0 is permittivity of free space, A is the area of Gaussian surface and qenc is charge enclosed by the Gaussian surface. This equation can be used in which of the following situation?
In the diagram, the total electric flux through the closed surface ‘S’ is:
[Given q = charge ε0 = permittivity of free space]
