Question

a closed loop carrying current I is placed in y-z plane. the loop experiences a zero torque in uniform magnetic field, then magnetic field is directed along

1) x axis

2) y axis

3) z axis

4) alonf -z axis

Answer 1

$$\begin{gathered} Torqueontheloopisgivenby: \\ \tau =m\times B \\ wheremisthemagneticmoment \\ \tau =mB\sin \theta \\ where\theta istheanglebetweenBansm. \\ if\tau =0 \\ themanglebetweenmandBis0 \\ somagneticfieldandmagneticmoementmustbeinsamedirection \\ whencurrentcarryingloopisplacediny-zdirectionthenmagneticmomentwouldbeindirection. \\ somagneticfieldmustbeinxdirection. \end{gathered}$$