A closed loop of magnetic field is produced by a changing electric field. Are electric field and time varing electric fiels necessarily non zero at all points on tte loop and in the area enclosed by the loop?

Maxwell's equation of Ampere's law is written as

where B is magnetic field induction, J is current density in the region of magnetic field, E is electric field , 

μ_o and ε_o are respectively permeability and permissivity of medium.

 

Second term in the right hand side is due to displacement current.

 

In integral form, above equation is written as,

Hence it can be inferred  from above integral equation, closed loop magnetic field is produced by

enclosed current of the loop and displacement current produced in the loop area due to change in electric field.

 

In the absence of enclosed current, closed loop magnetic field is produced only by time varying electric field

in the area enclosed by the loop