Magnetism Question 110
Question: Two magnets are held together in a vibration magnetometer and are allowed to oscillate in the earth’s magnetic field with like poles together, 12 oscillations per minute are made but for unlike poles together only 4 oscillations per minute are executed. The ratio of their magnetic moments is
[MP PMT 1996; CPMT 2002]
Options:
A) 3 : 1
B) 1 : 3
C) 3 : 5
D) 5 : 4
Show Answer
Answer:
Correct Answer: D
Solution:
In the sum and difference method of vibration magnetometer $ \frac{M _{1}}{M _{2}}=\frac{T _{2}^{2}+T _{1}^{2}}{T _{2}^{2}-T _{1}^{2}} $ Here $ T _{1}=\frac{1}{n _{1}}=\frac{60}{12}=5\sec .\ T _{2}=\frac{1}{n _{2}}=\frac{60}{4}=15\sec $
$ \
Therefore \frac{M _{1}}{M _{2}}=\frac{15^{2}+5^{2}}{15^{2}-5^{2}}=\frac{225+25}{225-25}=\frac{5}{4} $
BETA
