Question

A wire is carrying conventional current down a page in a uniform magnetic field that is directed into the page as shown above.
What is the direction of the magnetic force on the wire?

• A. Into the page
• B. Out of the page
• C. To the left
• D. To the right
• E. There is no magnetic force

Answer 1

Answer: (D)

To the right

Magnetic force on current carrying wire $\overrightarrow{F}=I(\overrightarrow{l}\times \overrightarrow{B})$

From figure, $\overrightarrow{l}=-l\hat{y}$ $\overrightarrow{B}=-B\hat{z}$

$\therefore$ $\overrightarrow{F}=I[-l\overrightarrow{y}\times (-B\left)\hat{z}\right]=IlB(\hat{y}\times \hat{z})=IlB$ $\hat{x}$

Hence the force acts in the right direction.