Question

A point charge is placed at the center of a spherical Gaussian surface. The electricflux ΦEischangedif(a) a second point charge is placed outside the sphere(b) the point charge is moved outside the sphere(c) the point charge is moved off center, but still inside the original sphere(d) the sphere is replaced by a cube of one-tenth the volume (the original charge remains in thecenter)

Answer 1

Answer:

(b) the point charge is moved outside the sphere

Explanation:

Gauss' Law states that the electric flux of a closed surface is equal to the enclosed charge divided by permittivity of the medium.

$\int\vec{E}d\vec{a} = \frac{Q_{enc}}{\epsilon_0}$

According to this law, any charge outside the surface has no effect at all. Therefore (a) is not correct.

If the point charge is moved off the center, the points on the surface close to the charge will have higher flux and the points further away from the charge will have lesser flux. But as a result, the total flux will not change, because the enclosed charge is the same.

Therefore, (c) and (d) is not correct, because the enclosed charge is unchanged.