Force between two parallel current carrying conductors
Let parallel conductors are I and II. I1, current is flowing through conductor I and I2through II.
The force experienced per unit length by the current carrying conductor I due to the magnetic field produced by the conductor II. Magnetic field at point P due to current I2Â is given by,
According to right hand thumb rule, the direction of the magnetic field B2Â at point P is perpendicular to the plane of paper and in inward direction.
Now the conductor I carrying current I1Â lies in the magnetic filed B2Â produced by the conductor I2.
Since, F = B I l
Hence,Â
F = B2 x (l1 x I) =Â
Force, F =Â
Definition of Ampere:
Let I1Â = I2Â = 1 A and a = 1 m
Then from above equation, we have
One ampere is the current which when flowing through each of the two parallel conductors of infinite length and placed in free space at a distance of 1 metre apart, produces between them a force of 2 x 10Â -7newton per metre of their lengths.