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Electricity and Magnetism

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Gauss' Law and Number of ELectrons

EANDM-9MBHQ4

A collection of electrons tightly bunched into a small spot are surrounded by a spherical surface at a distance of $1$ meter. The total flux measured through this surface is $\Phi = -40\,Nm^2 /C$.

How many electrons are there in the small spot?

A

$2.2 \times 10^{10}$

B

$1.6 \times 10^{19}$

C

$2.2 \times 10^{9}$

D

$3.5\times 10^{9}$