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The number of electric field lines emerging out from a 1 mC charge is ______. (ε₀=8.85×10⁻¹² C² N⁻¹ m⁻²)

Asked in GSEB Board March 2019 · Gauss's law and enclosed charge

Answer: (1) 1.13×10⁸

Step-by-step solution

Given: q=1 mC=10⁻³ C; ε₀=8.85×10⁻¹² C² N⁻¹ m⁻².

Idea: the number of field lines leaving a charge is taken equal to the electric flux through a closed surface around it, and Gauss's law gives that flux as φ=q/(ε₀).

N=q/(ε₀)=(10⁻³)/(8.85×10⁻¹²)

N=1.13×10⁸

So about 1.13×10⁸ lines emerge from the charge.

Why the other options are wrong

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