Suppose a point charge is located at the center of a spherical surface. The electric field at the surface of the sphere and the total flux through the sphere are determined.
1).What happens to the flux and the magnitude of The electric field if the radius of the sphere is halved?
Our teacher said the flux decreases and the filed increases.
A spherical gaussian surface surrounds a point charge $q$. Describe what happens to the: flux through the surface if
2) The radius of the sphere is doubled
Our teacher said the electric flux will not change
3) The shape of the surface is changed to that of a cube
Also the electric flux will not change
So why the electric flux changed in question 1 but in question 2 did not change? And when does the electric flux and electric field change?