Q. A string vibrates with a frequency of 200 Hz. When its length is doubled and tension is altered, it begins to vibrate with a frequency of 300 Hz. The ratio of the new tension to the original tension is

A) 9:1
B) 1:9
C) 3:1
D) 1:3
Explanation

(a) Frequency
$v = \frac{1}{2\iota}\sqrt{\frac{T}{m}}$
$\Longrightarrow \ \ \ \ \ \ v \propto \frac{\sqrt{T}}{\iota}$
$\frac{T_{2}}{T_{1}} = \left\lbrack \frac{v_{2}}{v_{1}} \right\rbrack^{2}\left\lbrack \frac{\iota_{2}}{\iota_{1}} \right\rbrack^{2}$
$= \left\lbrack \frac{300}{200} \right\rbrack^{2}\left\lbrack \frac{2\iota}{\iota} \right\rbrack^{2} = \frac{9}{1}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

Want more practice?
Practice Waves MCQs