question_answer

    A bar magnet has coercively\[4\times {{10}^{3}}A\text{ }{{m}^{-1}}\]. It is desired to demagnetize it by inserting it inside a solenoid 12 cm long and having 60 turns. The current that should be sent through the solenoid is

A)  2 A                                        

B)  4A

C)  6 A                                        

D)  8 A