Question 101: Magnetism and Matter

Question

A magnetic needle of magnetic moment 6.7 $$	imes$$ 10-2 A m2 and moment of inertia 7.5 $$	imes$$ 10-6 kg m2 is
performing simple harmonic oscillations in a magnetic field of 0.01 T. Time taken for 10 complete oscillations is:

Accepted Answer

Given : Magnetic moment, M = 6.7 ÃÂ 10
Ã¢ÂÂ2
Am
2
Magnetic field, B = 0.01 T
Moment of inertia, I = 7.5 ÃÂ 10
Ã¢ÂÂ6
Kgm
2
Using, T = $$2\pi \sqrt {{I \over {MB}}} $$
= $$2\pi \sqrt {{{7.5 	imes {{10}^{ - 6}}} \over {6.7 	imes {{10}^{ - 2}} 	imes 0.01}}} $$
= $${{2\pi } \over {10}} 	imes 1.06$$ s
Time taken for 10 complete oscillations
t = 10T = 2$$\pi $$ ÃÂ 1.06
= 6.6568 $$ \simeq $$ 6.65 s

Answer

8.76 s

Answer

6.65 s

Answer

8.89 s

Answer

6.98 s

Magnetism and Matter

A magnetic needle of magnetic moment 6.7 $\times 10-2 A m2 and moment of inertia 7.5 \times$ 10-6 kg m2 is performing simple harmonic oscillations in a magnetic field of 0.01 T. Time taken for 10 complete oscillations is:

Choose the correct answer: