A tuning fork produces 4 beats /sec, with a sonometer wire of length 40 cm. It is found that when the length is increased to 44 cm, by keeping other factors constant, again 4 beats/sec are produced. What is the frequency of the tuning fork ?

Options

A. 44 Hz
B. 84 Hz
C. 100 Hz
D. 176 Hz

Answer

B

Explanation

Let n be frequency of the tuning fork and `n_(1)` be the frequency of the wire .
` :. n_(1)/n_(2) = l_(2)/l_(1) = 11/10 :. N_(1) gt n_(2)`
` :. (n + 4)/(n - 4) = 11/10 :. N = 84 ` Hz