NEET-XII-Physics
05: Magnetism And Matter
- #7A bar magnet of magnetic moment 1.5 J T-1 lies aligned with the direction of a uniform magnetic field of 0.22 T.
(a) What is the amount of work required by an external torque to turn the magnet so as to align its magnetic moment: (a) normal to the field direction, (a) opposite to the field direction?
(b) What is the torque on the magnet in cases (i) and (ii)?Ans : null (a) Magnetic moment, M = 1.5 J T-1
Magnetic field strength, B = 0.22 T
(a) Initial angle between the axis and the magnetic field, θ1 = 0°
Final angle between the axis and the magnetic field, θ2 = 90°
The work required to make the magnetic moment normal to the direction of magnetic field is given as:
(a) Initial angle between the axis and the magnetic field, θ1 = 0°
Final angle between the axis and the magnetic field, θ2 = 180°
The work required to make the magnetic moment opposite to the direction of magnetic field is given as:
(b) For case (i):
∴Torque,
For case (ii):
∴Torque,
- #7-aWhat is the amount of work required by an external torque to turn the magnet so as to align its magnetic moment:Ans : Magnetic moment, M = 1.5 J T-1
Magnetic field strength, B = 0.22 T
- #7-a-inormal to the field direction,Ans : Initial angle between the axis and the magnetic field, θ1 = 0°
Final angle between the axis and the magnetic field, θ2 = 90°
The work required to make the magnetic moment normal to the direction of magnetic field is given as:
- #7-a-iiopposite to the field direction?Ans : Initial angle between the axis and the magnetic field, θ1 = 0°
Final angle between the axis and the magnetic field, θ2 = 180°
The work required to make the magnetic moment opposite to the direction of magnetic field is given as:
- #7-bWhat is the torque on the magnet in cases (i) and (ii)?Ans : For case (i):
∴Torque,
For case (ii):
∴Torque,