From chain rule,
d
d
d
d
d
d
d
d


t
t



 


Using this,
I  
d
sin
d
 m B




Integrating from q = 0 to q = p/2,
Example 4 12
(a) A current-carrying circular loop lies on a smooth horizontal plane Can a uniform magnetic field be set up in such a manner that
the loop turns around itself (i e