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12th Class Physics Magnetism Question Bank MCQ - Magnetism and Matter

  • question_answer
                A circular coil of 25 turns and radius of 12 cm is placed in a uniform magnetic field of 0.5 T normal to the plane of coil. If the current in the coil is 5A, then total torque experienced by the coil is:

    A) 1.5 N m                        

    B)             2.5 N m    

    C)             3.5 N m                        

    D)             zero         

    Correct Answer: D

    Solution :

    (d) zero                                              Here, \[N=15\text{ }turns,\text{ }r=12\text{ }cm,\text{ }B=0.5\text{ }T\] Since the coil is placed in uniform magnetic field normal to the plane of the coil.           Hence the angle between magnetic moment and magnetic field direction is zero (i.e., \[\theta =0{}^\circ \])                            \[\therefore \tau =MB\,\sin \theta =MB\,\sin 0{}^\circ \Rightarrow \tau =0\]


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