Question

The tuning fork and sonometer wire were sounded together and produce 4 beats/second when the length of sonometer wire is 95 cm or 100 cm. The frequency of tuning fork is

• A. 156 Hz
• B. 152 Hz
• C. 148 Hz
• D. 160 Hz

Answer 1

Answer: (A)

156 Hz

Answer 2

Frequency n $\propto \frac{1}{l}\therefore\text{As}n = \frac{1}{2l}\sqrt{\frac{T}{m}}$

If n is the frequency of tuning fork.

n + 4 $\propto \frac{1}{95}$⇒ n – 4 $\propto \frac{1}{100}$⇒ (n + 4 ) 95 = (n – 4) 100 ⇒ n = 156 Hz.