Question

A tuning fork 'A' produces 5 beats per second with a tuning fork of frequency 480 Hz. When a little wax is stuck to a prong of fork A, the number of beats heard per second becomes 2. What is the frequency of tuning fork A before the wax is stuck to it?

Options

• 475 Hz

• 482 Hz

• 478 Hz

• 485 Hz

Answer 1

485 Hz

Explanation:

Let f be the tuning fork A's frequency. The value of may then be 480 5 Hz, or 485 Hz or 475 Hz. When the same wax is hit against a prong of fork A, the frequency of the beats reduces. This is only feasible if the tuning fork's initial frequency is 485 Hz.

OR

Frequency of tuning fork B = 480 Hz. It produces 5 beats with tuning fork A. Therefore frequency of tuning fork A can be 485 Hz or 475 Hz. On loading, the tuning fork A with wax its frequency will decrease. Since the number of beats decreases, it means its frequency is higher than that of B. Hence its frequency is 485 Hz.