What is the wave intensity formula for sound?

AI Thread Summary
The formula provided by the physics teacher for calculating intensity, I = 2*(pi)^2*A^2*P*F^2*V, is not commonly found in standard physics literature. Intensity is typically defined as power per unit area, with the simpler formula I = P/A being widely accepted. The discussion highlights confusion regarding the teacher's formula and its derivation, suggesting that it may relate to the intensity of a plane wave. For further understanding, users are directed to resources on intensity in mechanical waves. Clarification from the teacher on the formula's context and derivation is recommended for better comprehension.
CoolGod
Messages
8
Reaction score
0
Our physics teacher gave us a formula to calculate intensity, she didn't really specify what intensity, it should be related to sound.
I = intensty
A = amplitude
P = Density
F = frequency
V = velocity
pi = 3.14
she said I = 2*(pi)^2*A^2*P*F^2*V
I can't find anything like this in books or internet, maybe I'm bad at searching.
I was wondering is she right and can she explain the formula? I get the simple I=P/A formula.
 
Physics news on Phys.org
This is the formula for the intensity of a plane wave with amplitude A, and frequency f, propagating with speed v.
You can find a complete derivation of the formula here

http://physics.info/intensity/

or just look up "intensity plane mechanical wave" or similar.
 
Formula to calculate intensity: I = V/A Where: I = intensity V = voltage A = area of the conductor Example: Calculate the intensity of the current in a 16 cm wire carrying a current of 2.0 A. Solution: I = V/A = 2 A = area of the conductor = 16 I = 2/16 = 0.125
 
Thread 'Gauss' law seems to imply instantaneous electric field propagation'

Thread 'Gauss' law seems to imply instantaneous electric field propagation'

Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla \cdot \mathbf{A} + \frac{1}{c^2}\frac{\partial \phi}{\partial t}=0\tag{1}$$ we find the following retarded solutions to the Maxwell equations If we assume that...
View full post »

Thread 'Do electron density waves accompany EM waves in coaxial cables?'

Maxwell’s equations imply the following wave equation for the electric field $$\nabla^2\mathbf{E}-\frac{1}{c^2}\frac{\partial^2\mathbf{E}}{\partial t^2} = \frac{1}{\varepsilon_0}\nabla\rho+\mu_0\frac{\partial\mathbf J}{\partial t}.\tag{1}$$ I wonder if eqn.##(1)## can be split into the following transverse part $$\nabla^2\mathbf{E}_T-\frac{1}{c^2}\frac{\partial^2\mathbf{E}_T}{\partial t^2} = \mu_0\frac{\partial\mathbf{J}_T}{\partial t}\tag{2}$$ and longitudinal part...
View full post »
Thread 'Recovering Hamilton's Equations from Poisson brackets'

Thread 'Recovering Hamilton's Equations from Poisson brackets'

The issue : Let me start by copying and pasting the relevant passage from the text, thanks to modern day methods of computing. The trouble is, in equation (4.79), it completely ignores the partial derivative of ##q_i## with respect to time, i.e. it puts ##\partial q_i/\partial t=0##. But ##q_i## is a dynamical variable of ##t##, or ##q_i(t)##. In the derivation of Hamilton's equations from the Hamiltonian, viz. ##H = p_i \dot q_i-L##, nowhere did we assume that ##\partial q_i/\partial...
View full post »

Similar threads

I Understanding the propagation of sound on molecular Scale
Replies
8
Views
2K
A Electric and magnetic field lines in a plane wave of finite extent
Replies
1
Views
1K
Max velocity of a vibrating loud speaker membrane given sound intensity
Replies
4
Views
2K
I Why is saxophone growling produced by modulation of the sound waves?
2
Replies
92
Views
5K
I Helmholtz resonator with multiple necks--formula?
Replies
10
Views
6K
I Sound pressure and inverse distance law
Replies
5
Views
2K
Sound wave intensity (dB) and sound processing
Replies
3
Views
2K
Relation between sound intensity and frequency
Replies
1
Views
8K
Use relativity and the Larmor formula to calculate Lienard's formula
Replies
2
Views
2K
Problem on Doppler effect and sound level
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top