question_answer

A hope and a solid cylinder of same mass and radius are made of a permanent magnetic material with their magnetic moment parallel to their respective axes. But the magnetic moment of hoop is twice of solid cylinder. They are placed in a uniform magnetic field in such a manner angle with the field. If the oscillation periods of hoop and cylinder are \[{{T}_{h}}\text{ }and\text{ }{{T}_{c}}\] respectively, then- [JEE Main 10-Jan-2019 Evening]

A) \[{{T}_{h}}=1.5\text{ }{{T}_{c}}\]

B) \[{{T}_{h}}={{T}_{c}}\]

C) \[{{T}_{h}}=2{{T}_{c}}\]

D) \[{{T}_{h}}=0.5{{T}_{c}}\]

Correct Answer: B

Solution :

[b]

Using