Consider the expression for magnetic potential energy `U_(m)` obtained in previous question, match the tems of colum I with the tems of Column II and choose the correct option from the codes given below.

Answer

A-R,B-P,C-Q

Explanation

Since the magnetic potential energy `U_(m)` is given by.
`" "U_(m)=m.B=-mB cos theta `
`A " " "For" theta=90^(@) Rightarrow U_(m)=-mB cos90^(@)=0`
`B " " "For" theta=0^(@), U_(m)=-mB cos0^(@)=-mB`
The potential energy is minimum and hence the middle the needle is in most stable position.
`C " " "For" theta=180^(@), U_(m)=-mB cos180^(@)=+mB`