question_answer

Two parallel conductors A and B of equal length carry currents i and 10 i, respectively, in the same direction. Then

A)  A and B will repel each other with same force

B)  A and B will attract each other with same force

C)  A will attract B, but B will repel A

D)  A and B will attract each other with different forces

Correct Answer: B

Solution :

The magnitude of force acting on. length\[l\]of each conductor due to other is Given    \[{{i}_{1}}=i,\,\,{{i}_{2}}=10i\] \[\therefore \]  \[\frac{F}{l}=\frac{{{\mu }_{0}}}{2\pi }=\frac{10{{i}^{2}}}{r}\] From Flemings left hand rule, this is force of attraction.