Q. Two instruments having stretched strings are being played in union. When the tension of one of the instruments is increased by 1%, 3 beats are produced in 2s. the initial frequency of vibration of each wire is
A) 300 Hz
B) 500 Hz
C) 1000 Hz
D) 400 Hz
Explanation
(a) Frequency
$v = \frac{1}{2l}\sqrt{\left( \frac{T}{m} \right)}\ $
$\therefore v + \frac{3}{2} = \frac{1}{2l}\sqrt{\left( \frac{101\ T}{100\ m} \right)}$
$= 1.005 \times \frac{1}{2l}\sqrt{\left( \frac{T}{m} \right)}$
⟹ v+1.5=1.005v
⟹ v=300 Hz
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.