For Gauss 'law mark out the corrrect statement(s)

Options

A. if we displace the enclosed charges (within a Gaussian surface )without crossing the boundary then `vec(E)` and `phi` both remain same.
B. if we displace the enclosed charges without crossing the boundary then `bar(E)` changes but `phi` remains the same.
C. if charge crosses the boundary then `phi` and `vec(E)` both changes.
D. If charge crosses the boundary, then `phi` changes but `vec(E)` remains the same.

Answer

B,C

Explanation

`phi` crossing through Gaussian surface does not depend on the location of charge while `vec(E)` depends on it.if `q` crosses the boundary,then `q_("enclosed")` and hence the flux and `vec(E)` also charge.