A source of sound of frequency 600 Hz is placed inside water. The speed of sound in water is 1500 m/s and in air, it is 300 m/s. The frequency of sound recorded by an observer who is standing in the air is:
Correct answer: D. 600 Hz
- A. 200 Hz
- B. 3000 Hz
- C. 120 Hz
- D. 600 Hz
Explanation
Frequency is determined by source oscillation and does not change when waves cross media. Observed frequency remains 600 Hz; only wavelength and speed change according to v = fλ.
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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.
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