Answer to Question #172750 in Physics for Jerick

Question #172750

  (a) Calculate the wavelengths in air at 20°C for sounds in the maximum range of human hearing, 20 Hz to 20,000 Hz. (b) What is the wavelength of an 18-MHz ultrasonic wave?


1
Expert's answer
2021-03-21T11:36:23-0400

(a) The speed of sound at 20°C equals 343 m/s343\ m/s. Then, we can find the wavelengths from the wave speed formula:


v=fλ,v=f\lambda,λ20 Hz=vf=343 ms20 Hz=17.15 m,\lambda_{20\ Hz}=\dfrac{v}{f}=\dfrac{343\ \dfrac{m}{s}}{20\ Hz}=17.15\ m,λ20 kHz=vf=343 ms20103 Hz=1.7102 m\lambda_{20\ kHz}=\dfrac{v}{f}=\dfrac{343\ \dfrac{m}{s}}{20\cdot10^3\ Hz}=1.7\cdot10^{-2}\ m

(b)

λ=vf=343 ms18106 Hz=1.9105 m.\lambda=\dfrac{v}{f}=\dfrac{343\ \dfrac{m}{s}}{18\cdot10^{6}\ Hz}=1.9\cdot10^{-5}\ m.

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!

Comments

No comments. Be the first!

Leave a comment