Question

what is magnetic field? how can the direction of magnetic field lines at a placed be determined

Answer 1

the magnetic field in which magnitude and direction of magnetic field at each point is Same is called magnetic field.
It is of two type
1-uniform magnetic field
2-non uniform magnetic field
the direction of magnetic field lines at any point on the magnetic field line is given by drawing a tangent at that point.

Mark it brillant if you like.

Answer 2

The magnetic field can be defined as:

“A region around/surrounded by a moving electric charge or a magnetic material within which the force of magnetism acts.”

How does Magnetic Field occur?

If you are wondering how Magnetic fields occur. Well, it occurs whenever a charge is in motion. That being said if you apply more charge in the motion the strength of a magnetic field usually increases. Besides, Magnetism and magnetic fields are part of the electromagnetic force which is indeed one of the four prime forces of nature.