B Ultrasonic wave and regular sound wave

  • B
  • Thread starter Thread starter Hesh123
  • Start date Start date
AI Thread Summary
The speed of sound in gases is influenced by temperature and is described by the formula v = √(γP/ρ), where γ is the specific heat ratio. This formula applies to all sound waves, including ultrasonic waves, as they are not fundamentally different in speed from normal sound waves. The distinction between normal and ultrasonic sound is based on frequency, not speed. In ideal gases, the speed of sound remains consistent across frequencies, with only minor variations in real gases. Therefore, the teacher's assertion about different formulas for normal and ultrasonic sound speed lacks context and is incorrect.
Hesh123
Messages
1
Reaction score
0
Does the speed of ultrasonic waves differ from the normal sound wave speed?
my teacher said that for normal sound wave speed v= √(γP/ρ)and for ultrasonic sound speed v= √(P/ρ) is he wrong?
 
Physics news on Phys.org
Welcome to PF.

In air, water, or in solids?
All low-amplitude sound waves propagate at the same speed, independent of frequency.

In a gas, the speed of sound is dependent on temperature. Large amplitude sound waves, where the pressure wave can change the instantaneous air temperature, can be distorted, or become shock waves.
 
  • Like
Likes Hesh123 and Lord Jestocost
I think gamma here is the ratio of the adiabatic to isothermal values for specific heat capacity. I will try to find out if there is a change as the frequency increases.
 
Hesh123 said:
is he wrong?
Yes, unless some context is missing. Ultrasound is just a name related to human hearing specifics. The formula without gamma was proposed by Newton and was latter corrected by Laplace by adding the gamma factor. The compression of air in a sound wave is better described as adiabatic rather than isothermal (as Newton assumed). The formula assumes an ideal gas, of course. In real gases there is a weak dependence of temperature and even weaker dependence on frequency.
 
  • Informative
  • Agree
Likes Hesh123 and berkeman
Hesh123 said:
Does the speed of ultrasonic waves differ from the normal sound wave speed?
my teacher said that for normal sound wave speed v= √(γP/ρ)and for ultrasonic sound speed v= √(P/ρ) is he wrong?
You can see from the reply by nasu #4 that your first formula applies at all frequencies.
 
Consider an extremely long and perfectly calibrated scale. A car with a mass of 1000 kg is placed on it, and the scale registers this weight accurately. Now, suppose the car begins to move, reaching very high speeds. Neglecting air resistance and rolling friction, if the car attains, for example, a velocity of 500 km/h, will the scale still indicate a weight corresponding to 1000 kg, or will the measured value decrease as a result of the motion? In a second scenario, imagine a person with a...
Scalar and vector potentials in Coulomb gauge Assume Coulomb gauge so that $$\nabla \cdot \mathbf{A}=0.\tag{1}$$ The scalar potential ##\phi## is described by Poisson's equation $$\nabla^2 \phi = -\frac{\rho}{\varepsilon_0}\tag{2}$$ which has the instantaneous general solution given by $$\phi(\mathbf{r},t)=\frac{1}{4\pi\varepsilon_0}\int \frac{\rho(\mathbf{r}',t)}{|\mathbf{r}-\mathbf{r}'|}d^3r'.\tag{3}$$ In Coulomb gauge the vector potential ##\mathbf{A}## is given by...
Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (First part)'
I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8 and stuck at some statements. It's little bit confused. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. Solution : The surface bound charge on the ##xy## plane is of opposite sign to ##q##, so the force will be...

Similar threads

Replies
5
Views
2K
Replies
6
Views
1K
Replies
14
Views
1K
Replies
236
Views
14K
Replies
3
Views
1K
Replies
42
Views
4K
Back
Top