Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
KVPY2011PhysicsWaves and Sound

A speaker emits a sound wave of frequency f₀ . When it moves towards a stationary observer with speed u , the observer measures a frequency f₁ . If the speaker is stationary, and the observer moves towards it with speed u , the measured frequency is f₂ . Then -

Options

  1. Af₁=f₂ < f₀
  2. Bf₁>f₂
  3. Cf₁ < f₂
  4. Df₁=f₂>f₀

Correct answer

B. f₁>f₂

Step-by-step solution

f ₁= f ₀[ v ] v - u f₂=f₀ [v+u] v f₂-f₁=f₀ ( u+v v - v v-u )f₂-f₁= -u² f₀ (v)(v-u) =-v e f₁>f₂

Practice Waves and Sound on Quantrex Academy →

More from Waves and Sound

Resonance is produced between a turning fork and a resonance column tube with upper end open and lower end closed by water surface. If the frequency of the tuning fork is 800Hz, an 2026The speed of transverse wave in aluminium wire is 1 10 times the speed of longitudinal wave in the wire. The stress in the wire is (Young's Modulus of Al = 10¹⁰ Pa) 2026A source of frequency gives 6 beats/second when sounded with a source of frequency 200 Hz. The second Harmonic of frequency 2 of the source gives 8 beats/second when sounded with a 2026A sound wave of frequency 500 Hz travels between two points X and Y separated by a distance of 600 m in a time of 2 s. The number of waves between the points X and Y are 2025When both source of sound and observer approach each other with a speed equal to 10 % of the speed of sound, then the percentage change in frequency heard by the observer is nearly 2025The equation of a transverse wave propagating along a stretched string of length 80 cm is y =1.5 (5 10⁻³ x )+20 t , here ' x ' and ' y ' are in cm and the time ' t ' is in second. 2025If a travelling wave is given by y(x, t)=0.5 (70.1 x-10 t) , where x and y are in metre, the time t is in second, then the frequency of the wave is 2025In a closed organ pipe, the number of nodes formed in fifth and ninth harmonics are respectively 2025 Full Waves and Sound list All KVPY PYQs