Q.
Two parallel wires carrying currents in the same
direction attract each other because of
Solution:
As shown in the figure, let the conductor Y
carry current $I_2, $ situated in a magnetic field B
perpendicular to its length. It therefore,
experiences a magnetic force, the magnitude
of the force acting on a length l of Y is
$ F=I_2Bl=I_2\bigg ( \frac {\mu _0}{2 \pi}\frac {I_1}{R}\bigg )l$
From Fleming's left hand rule the direction of this force is
towards X. Similarly, force per unit length of X due to Y is
directed opposite to Y.
Hence, the conductors attract each other.
