Concepts Of Physics MCQ Edition [Volume 2]PhysicsPermanent Magnets
For measuring the magnetic moment of a bar magnet, one could use
Options
- Aa tangent galvanometer
- Ban oscillation magnetometer, provided the earth's horizontal field is known
- Ca deflection galvanometer, provided the earth's horizontal field is known
- Dboth deflection and oscillation magnetometer, if the earth's horizontal field is not known
Correct answer
D. both deflection and oscillation magnetometer, if the earth's horizontal field is not known
Step-by-step solution
The time period of oscillation of a bar magnet in an oscillation magnetometer is given by T = 2 I MB_H . This gives the product MB_H = 4 ^2 I T^2 . If the earth's horizontal magnetic field B_H and the moment of inertia I are known, the magnetic moment M can be determined. In a deflection magnetometer, the deflection is related to M and B_H by M B_H = k , where k is a constant depending on the position (Tan A or Tan B). If B_H is known, M can be determined. If B_H is not known, we can use both instruments. The oscil