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The electric flux from a unit positive charge kept in a cuboidal box is:
1. ϵ0-1
2. 4πϵ0
3. ϵ0
4. 4πϵ0-1

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Correct Answer - Option 1 : ϵ0-1

The correct answer is option 1) i.e. ϵ0-1


  • Gauss's Law for electric field: It states that the total electric flux emerging out of a closed surface is directly proportional to the charge enclosed by this closed surface. It is expressed as:

\(ϕ = \frac{q}{ϵ_0}\)

Where ϕ is the electric flux, q is the charge enclosed in the closed surface and ϵ0 is the electric constant.


Since a unit positive charge is given, q = +1 unit.

Therefore, electric flux from the surface \(ϕ = \frac{q}{ϵ_0} = \frac{1}{\epsilon_0} = \epsilon_0^{-1}\)

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