Wave Mechanics Question 745
Question: The tension of a stretched string is increased by 69%. In order to keep its frequency of vibration constant, its length must be increased by
[KCET 2002]
Options:
A) 20%
B) 30%
C) $ \sqrt{69}% $
D) 69%
Show Answer
Answer:
Correct Answer: B
Solution:
$ n\propto \frac{\sqrt{T}}{l} $
$ \Rightarrow l\propto \sqrt{T} $ (As $ n $ = constant)
Therefore $ \frac{l _{2}}{l _{1}}=\sqrt{\frac{T _{2}}{T _{1}}}=l _{1}\sqrt{\frac{169}{100}}\Rightarrow l _{2}=1.3l _{1}=l _{1}+30% $ of $ l _{1} $
BETA
