CBSE Class 12-science Answered

Dear student,

C₁D₁ and C₂D₂, two infinite long straight conductors carrying current I₁ and I₂ in the same direction. They are held parallel to each other at a distance r in the plane of paper.
Magnetic Field induction at point P on C₂D₂ due to current passing through C₁D₁ is given by,

B₁ = μ_o/ 4 π  (2 l₁/r)

As the current carrying conductor C₂D₂ lies in the magnetic field B1 therefore, unit length of
C₂D₂ will experience a force F₂ = B₁I₂ x 1 = B₁I₂

F2 = μ_o/ 4 π (2 l₁ l₂/r)

According to Fleming’s left hand rule force on conductor C2D2 acts in the plane of the paper and directed towards C1D1. Similarly, it can be shown that the conductor C1D1 experiences a force which is directed towards C2D2 and hence they attract each other. If the current in the conductors C1D1 and C2D2 are in opposite directions they repel each other with the same force.