Two point charges Q1 = 10 μC and Q2 = 20 μC are placed

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Two point charges Q₁ = 10 μC and Q₂ = 20 μC are placed at coordinates (1, 1, 0) and (– 1, – 1, 0) respect ively. The total electric flux passing through a plane z = 20 will be

1. 7.5 μC
2. 13.5 μC
3. 15.0 μC
4. 22.5 μC

Correct Option: C

By Gauss’s law,
∮ D .ds = Q_end = Ψ
Which states that the “ total flux out of a closed surface is equal to the net charge within the surface”.

Half of the flux will bass through the plane at z = 20 and the other half through the plane at z = – 20

Then, Ψ' =	Q_end	=	20 + 10	μc = 15 μ c
	2		2