Two tuning forks A and B are sounded together giving rise to 8 beats in 2 s. When fork A is loaded with wax, the beat frequency is reduced to 4 beats in 2 s. If the original frequency of tuning fork B is 380 Hz then original frequency of tuning fork A is

Q. Two tuning forks A and B are sounded together giving rise to 8 beats in 2 s. When fork A is loaded with wax, the beat frequency is reduced to 4 beats in 2 s. If the original frequency of tuning fork B is 380 Hz then original frequency of tuning fork A is ______ Hz.

Correct Answer: 384

Solution

Beat frequency is equal to the absolute difference of frequencies of the two tuning forks.

Initial beat frequency = 8 / 2 = 4 Hz

Let the original frequency of tuning fork A be f. Given frequency of tuning fork B is 380 Hz.

|f − 380| = 4

So possible values of f are 384 Hz or 376 Hz.

When wax is loaded on fork A, its frequency decreases. New beat frequency:

4 / 2 = 2 Hz

This means the difference between frequencies has reduced, so original frequency of A must be greater than 380 Hz.

Therefore, f = 384 Hz

Hence, the original frequency of tuning fork A is 384 Hz.

Related JEE Main Physics Questions

A fly wheel having mass 3 kg and radius 5 m is free to rotate about a horizontal axis. A string having negligible mass is wound around the wheel and the loose end of the string is connected to 3 kg mass. The mass is kept at rest initially and released. Kinetic energy of the wheel when the mass descends by 3 m is ______ J. (g = 10 m/s²)

A beam of light consisting of wavelengths 650 nm and 550 nm illuminates the Young's double slits with separation of 2 mm such that the interference fringes are formed on a screen, placed at a distance of 1.2 m from the slits. The least distance of a point from the central maximum, where the bright fringes due to both the wavelengths coincide, is ______ × 10⁻⁵ m.

An inductor stores 16 J of magnetic field energy and dissipates 32 W of thermal energy due to its resistance when an a.c. current of 2 A (rms) and frequency 50 Hz flows through it. The ratio of inductive reactance to its resistance is ______. (π = 3.14)

Number of photons of equal energy emitted per second by a 6 mW laser source operating at 663 nm is ________. (Given : h = 6.63 × 10⁻³⁴ J.s and c = 3 × 10⁸ m/s)

In an experiment, a set of reading are obtained as follows - 1.24 mm, 1.25 mm, 1.23 mm, 1.21 mm. The expected least count of the instrument used in recording these readings is ______ mm.

JEE Main Chapter-wise Previous Year Questions