If 20 sound waves pass from a point of a medium in 2 s with the velocity of 20 m/s, then the wavelength is
Correct answer: B. 2 m.
- A. 1 m.
- B. 2 m.
- C. 10 m.
- D. 20 m.
Explanation
To find the wavelength, start by calculating the frequency: 20 sound waves pass in 2 seconds, so the frequency is 20 waves / 2 s = 10 Hz. The wave equation relates velocity (v), frequency (f), and wavelength (λ) as v = f × λ. Substituting the given values (velocity = 20 m/s and frequency = 10 Hz), we have: 20 m/s = 10 Hz × wavelength. Solving for wavelength gives λ = 2 m, thus Option B is correct. Options A, C, and D result from errors in calculating the frequency or misapplying the wave equation.
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About Wave Speed
Wave speed is the rate at which a disturbance or wave pattern travels through a medium, given by v = fλ, where f is frequency and λ is wavelength. Questions examine how speed changes between media, the relation among frequency, wavelength and period, and why wave speed is not the same as particle vibration speed.
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