question_answer

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 F, the force on the arm AC is                                    

A) \[-\mathbf{F}\]

B)                        \[\mathbf{F}\]

C) \[\sqrt{2}\mathbf{F}\]                 

D)        \[-\sqrt{2}\mathbf{F}\]

Correct Answer: A

Solution :

     \[{{\mathbf{F}}_{AB}}=0\] \[{{\mathbf{F}}_{AB}}+{{\mathbf{F}}_{BC}}+{{\mathbf{F}}_{CA}}=0\] \[{{F}_{BC}}+{{F}_{CA}}=0\] \[{{F}_{CA}}=-{{F}_{BC}}=-F\]