Question

A wire carrying a current I along the positive x-axis has length L. It is kept in a magnetic field $\vec{B}=(2\vec{i}+3\vec j-4\vec k)T$. The magnitude of the magnetic force acting on the wire is:

• A. $\sqrt5 IL$
• B. 5 IL
• C. $\sqrt3 IL$
• D. 3 IL

Answer 1

Answer: (B)

5 IL

Answer 2

The correct option is (B): 5 IL

$\vec{F}=I(\vec{l}\times\vec{B})$

$I[(L\hat{i})\times(2\hat i+3\hat j-4\hat k)]$

$=I(4L\hat j+ 3L\hat k)$

$|\vec{F}|=5\,IL$