Question

Dotted surfaces are Gaussian surfaces and solid surfaces are material bodies. All the surfaces are spherical.

Answer 1

In (A) Field at point A is zero only in case 3. Now since other cases at point A are fundamental. In 3 we see that a dipole is placed at center of the sphere therefore, therewill be no any field outside the sphere since sphere acts as a shield for the dipole. Therefore, field outside the metallic sphere is zero therefore, field is zero at point A. (A)->3

In (B) As since charge is placed outside the sphere in 4 therefore field inside the sphere will be zero . Therefore, field at point B in 4 is zero.(B)->4

In (C)Since Charge enclosed inside the surface 1 in 1 is zero therfore flux linked with surface 1 is zero. Similarly in 3 and 4 also. Therefore, (C)->1,3,4

In (D) Charge enclosed through surface 2 is zero in only 4 therefore, flux through surface 2 is zero in 4. hence (D)->4