wave_mechanics mock_test_waves_and_acoustics Question 1
Question: Two identical straight wires are stretched so as to produce 6 beats per second when vibrating simultaneously. On changing the tension in one of them, the beat frequency remains unchanged. Denoting by $ T _{1} $ , $ T _{2} $ , the higher and the lower initial tensions in the strings, then it could be said that while making the above change in tension
Options:
A) $ T _{2} $ was decreased
B) $ T _{2} $ was increased
C) $ T _{1} $ was increased
D) $ T _{1} $ was kept constant
Show Answer
Answer:
Correct Answer: B
Solution:
[b] Using $ n=\frac{1}{2l}\sqrt{\frac{T}{m}}; $ As $ T _{1}>T _{2}\Rightarrow n _{1}>n _{2} $ giving $ n _{1}-n _{2}=6 $ The beat frequency of 6 will remain fixed when (i) $ n _{1} $ remains same but $ n _{2} $ is increased to a new value $ (n{’ _{2}}-n _{2}=12) $ increasing tension $ T _{2} $ .
(ii) $ n _{2} $ remains same but $ n _{1} $ is decreased to a new value $ (n _{1}-n{’ _{1}}=12) $ by decreasing tension $ T _{1} $ .
BETA
