Electrical Engineering ⇒ Topic : Magnitude of Mutual Force

Magnitude of Mutual Force

Fig. A (i) shows two parallel conductors placed in air and carrying currents in the same direction. Here I₁ and I₂ are the currents in conductors 1 and 2 respectively, 1 is the length of each conductor in metres and d is the distance between conductors in metres. It is clear that each of the two parallel conductors lies in the magnetic field of the other conductor.

                                                                                    Figure (A)

In order to determine the magnitude of force, we can consider conductor 2 placed in the magnetic field produced by conductor 1 as shown in Fig. A (ii). Now field intensity H due to current  I₁ in conductor 1 at the centre of conductor 2 is given by

It can be easily shown that conductor 1 will experience an equal force in the opposite direction

[See Fig. A (ii)].Force per metre run of the conductor is given by

According to Fleming's left-hand rule, the two conductors will attract each other.