Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main20199 Jan 2019Evening ShiftPhysicsWaves and SoundActual

A musician using an open flute of length 50 cm produces second harmonic sound waves. A person runs towards the musician from another end of a hall at a speed of 10 km h - 1 . If the wave speed is 330 m s - 1 , the frequency heard by the running person shall be close to

Options

  1. A333   Hz
  2. B500   Hz
  3. C666   Hz
  4. D753   Hz

Correct answer

C. 666   Hz

Step-by-step solution

Frequency of the observer, f o = 2 × v 2 l = 330 0.5   Hz = 660   Hz Velocity of person = 10   km   h - 1 = 10 × 5 18   m   s - 1 = 2.8   m   s - 1 According to Doppler effect, frequency heard by the person, f = f o v + v 0 v f = 660 × 330 + 2.8 330   Hz = 666   Hz

Practice Waves and Sound on Quantrex Academy →

More from Waves and Sound

List-I shows four configurations made of straight and semi-circular narrow tubes containing air. A sound wave of wavelength = 0.29 m enters these structures at the point S and a so 2026A transverse wave on a string is described by y = 3 (36t + 0.018x + /4) , where x, y are in cm and t in seconds. The least distance between the two successive crests in the wave is 2026The equation of a plane progressive wave is given by y = 5 (200t - x 150 ) where x and y are in cm and t is in second. The velocity of the wave is _______ m/s. 2026The speed of a longitudinal wave in a metallic bar is 400 ~m / s . If the density and Young's modulus of the bar material are increased by 0.5 % and 1 % , respectively then the spe 2026Two 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 freque 2026A point source is kept at the center of a spherically enclosed detector. If the volume of the detector increased by 8 times, the intensity will 2026The fifth harmonic of a closed organ pipe is found to be in unison with the first harmonic of an open pipe. The ratio of lengths of closed pipe to that of the open pipe is 5 / x . 2026The velocity of sound in air is doubled when the temperature is raised from 0^ C to ^ C . The value of is _ _ _ _ . 2026 Full Waves and Sound list All JEE Main PYQs