Question

A current carrying closed loop in the form of a right angle isosceles triangle $ABC$ is placed in a uniform magnetic field acting along $AB$. If the magnetic force on the arm $BC$ is $\vec{F}$, the force on the arm $AC$ is

• A. $-\sqrt2\, \vec{F}$
• B. $-\vec{F}$
• C. $\vec{F}$
• D. $\sqrt2 \,\vec{F}$

Answer 1

Answer: (B)

$-\vec{F}$

Answer 2

From $\vec{ F }= I (\vec{\ell} \times \vec{ B })$
$\vec{ F }_{ BC }=-\vec{ F }_{ AC }$
$\vec{ F }_{ AC }=-\vec{ F }$