A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?

Given:


Current through the wire, I = 90 A (East to West)


Distance of point P below the wire, d = 1.5 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| = 1.2 × 10-5T


Direction of magnetic field,


We know that wire carries current in east to west direction. Using Right hand thumb rule, we can conclude that the direction of magnetic field is from north to south as indicated in the figure.


The magnitude of the magnetic field is 1.2 × 10-5T and its direction is from north to south.


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