A long straight wire in the horizontal plane carries a current of 50 A in north to south direction. Give the magnitude and direction of B at a point 2.5 m east of the wire.

Given:

Current through the wire, I = 50 A (North to South)


Distance of point P East of the wire, d = 2.5 m



Using Biot Savart law we can find magnetic field at a distance d from a current carrying conductor.


It is given by:


…(1)


Where,


B = Magnetic field strength


I = current through the coil


�0 is the permeability of free space.


�0 = 4 × π × 10-7 TmA-1


d = distance of point P


By plugging the values in the equation (1), we get



⇒ |B| = 4 × 10-6T


Direction of magnetic field,


The point is in a plane normal to the wire and the wire carries current in north to south. Using Right hand thumb rule we can conclude that the direction of magnetic field is vertically upwards, or out of the paper.


The magnitude of the magnetic field is 4 × 10-6T and its direction is upwards or out of paper.


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