It might sound naive but the question is:
In an Electromagnetic wave in a vacuum the electric and magnetic fields are vibrating but what are the source and drain of these fields?
An electric field must start from a charge and end or be in a circular fashion due to varying magnetic field and in a similarly way, magnetic fields must form a closed loop.
Please explain this idea?
if magnetic fields are to be in closed loop always then the oscillating fields of a em waves must be too.
So what is the shape of fields in general near a em wave?