Question

a loop , A straight wire carries a 6.0A current that is directed in a positive x direction. When a uniform magnetic fileld is applied perpendicular to a 3.0 m segment of a site. the magnetic force on the segment is 0.36 N, directed in the negative y direction . what is the magnitude and direction of the magnetic field?

Answer 1

Since the ampere force (magnetic force) is equal to $F_A=B\times I\times l\times\sin\alpha$ , where $B$ is magnetic induction (magnitude characterizing magnetic field), $I$ is current strength, $l$ is the length of the conductor, $\alpha$ is the angle between vectors $\vec{I}$ and $\vec B$ , therefore

$B =\frac {F_A}{I\times l\times\sin\alpha}$ $=\frac {0.36}{6\times 3 \times\sin (90\degree)}=0.02$ T.

According to the law of the left hand, the direction of magnetic induction will be directed in the negative direction of the $Z$ axis.