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Question
A point charge causes an electric flux of −1.0 × 103 Nm2/C to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge.
- If the radius of the Gaussian surface were doubled, how much flux would pass through the surface?
- What is the value of the point charge?
Solution
- The electric flux passing through a spherical Gaussian surface drawn around a point charge does not depend on its radius, so even if the radius is doubled, the electric flux passing through it will remain -1.0 × 108 newton-m2/coulomb.
- Φ = `q/ε_0`
or q = Φ ε0
or q = -1 × 103 × 8.85 × 10-12
or q = -8.85 × 10-9 C
= -8.85 nC
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