A current carrying loop is placed in a uniform magnetic field in four different orientations , I,ii,iii & iv arrange them in the decreasing order of potential Energy`

Options

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

Answer

B

Explanation

Potential energy, `U=-vec(M).vec(B)=-mB sin theta`
`1. U=-MBcos 180^(@)=MB`
`2. U=-MBcos 90^(@)=0`
`3. U=-MBcos 90^(@)`
`4. U=+MBcos`