Discussion Forum



1)

 A conductor (shown in the figure) carrying constant current I in kept in the x-y plane in a uniform magnetic field B. If F is the magnitude of the total magnetic force acting on the conductor, then the correct statements is /are

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A) if B is along $\hat{z},F \infty (L+R)$

B) if B is along $\hat{x},F =0$

C) If B is along $\hat{y},F \infty(L+R)$

D) if B is along $\hat{z},F =0$

Answer:

Option A,B,C

Explanation:

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Force on the complete wire = force on straight wire PQ carrying a current I.

    $F=I(PQ \times B)$

              $=I\left[\left\{2(L+R)\hat{i}\right\} \times B\right]$

This force is zero if B  is along  $\hat{i}$  direction or x-direction . If magnetic  field is along $\hat{j}$  direction or $\hat{k}$  direction,

                  $|F|=F=(I)(2)(L+R)B\sin 90^{0}$

         or              F= 2I(L+R)B

 or            $F \infty(L+R)$

 $\therefore$     Options (a),(b) and (c) are correct.