Magnetic field

(a)       The space around a magnet in which a torque acts on a magnetic needle is known as magnetic field.

(b)       The space around a magnet in which a net force acts on a magnetic test pole is known as magnetic field.

(c)        The space around a magnet in which its effect is experienced is known as magnetic field.

            (i)         Uniform magnetic field:

                       (a) The magnetic field, in which the intensity of  magnetic field is same at all points, is known as uniform magnetic field.

                       (b) In such a magnetic field the magnetic lines of force are parallel and equidistant. e.g. the magnetic dines of force of earth's magnetic field.

           (ii)        Non-uniform magnetic field:

                      (a) The magnetic field, in which the intensity of magnetic field at different points is different, is known as non-uniform magnetic field.

                       (b) It is represented by non-parallel lines of force.

          (iii)       Varying magnetic field:

                       (a) The magnetic field, which keeps on changing with respect to time is known as a variable magnetic field.

                       (b) Example :– B = B₀ sin ω t  or         B = B₀ cos ω t

          (iv)       Non-varying magnetic field:

                      (a) The magnetic field which does not change with time is known as a constant magnetic field.

                      (b) The direction of magnetic field is that in which a force acts on a unit test pole.

                      (c) It can be produced by moving charges, current carrying loops, and variations in electric currents.