Question

A current carrying loop is placed in a uniform magnetic field in four different orientations as shown in figure. Arrange them in the decreasing order of potential energy.

• A. 4,2,3,1
• B. 1,4,2,3
• C. 4,3,2,1
• D. 1,2,3,4

Answer 1

Answer: (B)

1,4,2,3

Answer 2

: Potential energy, ,

(1) $\mathrm { U } = - \mathrm { MB } \cos 180 ^ { \circ } = \mathrm { MB }$

(2) $\mathrm { U } = - \mathrm { MB } \cos 90 ^ { \circ } = 0$

(3)

(4) $\mathrm { U } = + \mathrm { MB } \cos \theta$