CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

A magnet is suspended in the magnetic meridian with an untwisted wire. The upper end of wire is rotated through 180 to deflect the magnet by 30 from magnetic meridian. When this magnet is replaced by another magnet, the upper end of wire is rotated through 270 to deflect the magnet 30 from magnetic meridian. The ratio of magnetic moments of magnets is 
  1. 1 : 5
  2. 1 : 8
  3. 5 : 8
  4. 8 : 5


Solution

The correct option is C 5 : 8
Let M1 and M2 be the magnetic moments of magnets and H the horizontal component of earth's field. 
We have τ=MHsinθ. If ϕ is the twist of wire, then τ=Cϕ C being restoring couple per unit twist of wire
 Cϕ=MHsinθ
Here ϕ1=(18030)=150=150×π180rad
ϕ2=(27030)=240=240×π180rad
So, Cϕ1=M1H sinθ (For deflection θ=30 of I magnet)
Cϕ2=M2H sinθ (For deflection θ=30 of II magnet)
Dividing 
ϕ1ϕ2=M1M2
 M1M2=ϕ1ϕ2=150×(π180)240×(π180)=1524=58
 M1:M2=5:8

flag
 Suggest corrections
thumbs-up
 
0 Upvotes


Similar questions
View More


People also searched for
View More



footer-image