Q.

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole moment m. Which configuration has highest net magnetic dipole moment                  [2014]


 

1 (1)  
2 (2)  
3 (3)  
4 (4)  

Ans.

(3)

The direction of magnetic dipole moment is from south to north pole of the magnet.

In configuration (1),

mnet=m2+m2+2mmcos90°=m2+m2=m2

In configuration (2),

In configuration (3),

mnet=m2+m2+2mmcos30°=2m2+2m2(32)=m2+3

In configuration (4),

mnet=m2+m2+2mmcos60°=2m2+2m2(12)=m3