When a thin bar magnet of magnetic moment M is bent in the form of   S  shape  with the arms of equal length as shown in figure, then its new magnetic moment is

If the magnet is bent in the above shape magnetic length changes but pole strength remains   constant .Initially, M = ml Finally , M1=m(AF)From    ΔAFE,AF2=(AE)2+(FE)2                             ⇒(AF)2=2l52+l52                             ⇒(AF)2=4l225+l225=5l225=l25                           ⇒AF=l5Hence,       M1=m (AF)=ml5=M5         (M=ml)