What is Mean free path: Definition and 61 Discussions
In physics, mean free path is an average distance over which a moving particle (such as an atom, a molecule, a photon) substantially changes its direction or energy (or, in a specific context, other properties), typically as a result of one or more successive collisions with other particles.
Homework Statement
Hi, It's not a homework question, but as i am a beginner in physics, I prefer to post here first :
I try to evaluate thermal resistance at low temperature. I need to compute the mean free path of both electron and phonon in metals, but I do not find any formulas. Can...
Homework Statement
Hi, I am not sure about the following question:
(Q) Argon (atomic weight 40) exists as a monatomic gas at room temperature and pressure. The density of liquid argon is 1784kg/m^3.
(a) Calculate the atomic density (atoms/m^3) in liquid argon *Done*
(b) Hence...
Homework Statement
(a)What is the mean free path for oxygen molecules at 300K and atmospheric
pressure (105 Pa) and the average frequency of collisions for a particular molecule?
(The diameter of an oxygen molecule is 0.29 nm).
(b)What is the mean free path of oxygen molecules at an...
Could someone explain mean free electron paths with regard to;
Drude model
and Fermi velocity
I have answered a question where you are given relaxation time and fermi velocity at 4K and 300K and asks you to work out the mean free path. Easy. Next it says how do these values compare with what...
right this is the question. at a temperature of 300K and 1atm the density of air is 1.29kgm^-3 and the co-eff of viscosity is 1.75x10^-5Pas. Air has a molecular weight of 29 and the average speed is given by the square root of 8kt/piem.
what is their mean free path.
Homework Equations...
Why is average relative velocity equal to the square root of 2 times the magnitude of the x direction velocity?
I'm trying to solve some problems that deal with gas laws from Ideal gases to the Van der Waals gases.
Does anybody have any ideas?
Thanks.
Homework Statement
My solid-state physics book (Kittel) talks about the phonon mean free path (on page 122) but never defines it. Can someone please give me a definition?
I know what a mean free path is for a non-quasi-particle but I do not see how that extends to phonons.
Homework Equations...
Homework Statement
Neutral atomic hydrogen cloud, density n_H. Absorption cross section \sigma_{0} = 6.3*10^{-18}cm^{2}. Determine the mean free path of photons with energy of 20eV, for densities n_H = 1, 10 and 100 cm^{-3}. Compare this to mfp for photons with ionisation energy of hydrogen...
Let's say that we have Na at room temperature. The concentration of Na becomes plus one percent due to impurities. I'm interested in finding the mean free path and collisional cross section due to these impurities. I'm not sure on how Matheissen's rule could be applied, if we don't know what the...
Mean Free Path of an Electron -- URGENT
An electron can be thought of as a point particle with zero radius.
Find an expression for the mean free path of an electron through a gas.
The mean free path of an electron can be represented by:
\lambda = \frac{1}{\sqrt{2} \pi \frac{N}{V} r^2}...
I was hoping somebody could help me out with this problem I'm stuck on:
So in a mass spectrometer, an ionizing current of 2 pA causes ions of Cs+ to be produced. these ions have an energy of about 10 kev. I need to find the average distance (mean free path) between any two Cs+ ions at this...