Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole moment\[\vec{m}.\]Which configuration has highest net magnetic dipole moment?
a.
b.
c.
d.
A) 1
B) 2
C) 3
D) 4
Correct Answer:
C
Solution :
a. b. \[\underset{m}{\overset{m}{\longleftrightarrow}}\Rightarrow {{M}_{2}}=0\] c. \[{{M}_{3}}=m\sqrt{{{\left( 1+\cos {{30}^{o}} \right)}^{2}}}\] \[=m\sqrt{\left( 1+\frac{\sqrt{3}}{2} \right)2=m\sqrt{2+\sqrt{3}}}\] d. \[{{M}_{4}}=2m\cos {{30}^{o}}=m\sqrt{3}\]