A source of sound and a listener are both moving in the same direction, the source following the listener. If the respective velocities of sound, source, and listener are vr, vs , and vl , then the ratio of the actual frequency of the source and the apparent frequency as received by the listener is:
Correct answer: C. (V-Vs)/(V-Vl)
- A. (V-Vl)/ (V-Vs)
- B. V+Vl)/ (V+Vs)
- C. (V-Vs)/(V-Vl)
- D. (V+Vs)/( V+Vl)
Explanation
The Doppler effect formula for frequency is f′=v±v/s v±vr ×f, where f′ is the apparent frequency, f is the actual frequency, vr is the velocity of the receiver (listener), and vs is the velocity of the source. Here, both source and listener move, but the listener is following the source. Hence, vr =vl . Therefore, the correct ratio is (c) (V-Vs)/(V-Vl)
Last updated
About Waves
Progressive waves transfer energy through oscillations, with wavelength, frequency, amplitude and wave speed related by v = fλ; sound speed depends on the medium. Superposition produces interference and stationary waves in strings and organ pipes, while simple harmonic motion describes the oscillation itself and must be distinguished from wave propagation.
Practise Waves
1,281 free Waves MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 15 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
20 waves pass through a point in a medium, in 5 seconds. What is the time required for one wave to pass?
A 100 cm long string fixed at its two ends is plucked from the middle. The wavelength of stationary waves generated is:
A 100 cm long string fixed at its two ends is plucked from the middle. The wavelength of stationary waves generated is:
A 200 cm organ pipe with one end open is in resonance with a sound wave of wavelength 270 cm. The pipe is operating in its:
A car moving at 30 m/s toward an observer sounds its horn at 400 Hz. If the speed of sound is 343 m/s, what frequency does the observer hear?