Medium Definition and 390 Threads

[b]1.Find the speed of light in the following in m/s... (a) water (n = 1.33) (b) diamond (n = 2.42) (c) quartz (n = 1.54) i can't seem to get any of these right...

Homework Statement In the case of total internal reflection, show that the average rate of energy transport across the boundary is zero. Homework Equations None Provided The Attempt at a Solution All that I have come to is that I should use some form of the following method to find...

Why does the Lagrangian density for the EM field in a dielectric medium take the form d^3 \bf x \left[ \epsilon \bf E^2 - \bf B^2 \right]? I can see that the expression for Lagrangian density has units of energy per unit volume as you would expect but that's about it. Much appreciated.

Show that the action integral for the electromagnetic field in a matter with dielectric constant \epsilon is given by S_m=\frac{1}{8 \pi} \int dt d^3 \bf x \left[ \epsilon \bf E^2 - \bf B^2 \right] where the standard expressions for the E field and B field E=-\frac{1}{c}\partial_t \bf A -...

If everywhere in the universe is at above 0 degrees Kelvin, then there must be some degree of heat everywhere, so this could be considered a universal medium or not, and if what I heard about the sound of the big bang still reverberating throughout the universe is correct (see my contribution to...

I don´t understand how sound propogates. Is this also an inconsistent medium throughout the universe and could a ship be translated on sound stages? Is the sound from the big bang also inconsistant throughout the universe and if it isn´t and other aspects of sound vary throughout the...

Hi all, I am writing you because in my research I need to characterize the space environment for an interstellar flight from the Earth to Alpha Centauri (more exactly proxima centauri). So i need densities of atoms and ions (in terms of cm^-3), energies (MeV), magnetic field strength...

Hi guys, I need to find material compatibility to carbon steel AISI 1045 that is available locally. The closest that I can find is the SWRH 42A. All of the chemical composition matches (C, Si, P, S), except for Mn. AISI 1045 has Mn content of 0.60 - 0.90, while SWRCH 42A has Mn content of...

hello, this has stumped me and i think there is something weird going on my definition of reference frames: lets look at two scenarios: scenario1:sound emitter and observer are both moving with velocity x in the same direction in a stationary medium... no doppler shift is expected...

here's the problem: 2 vibrating sources emit waves in the same elastic medium. the first source has a frequency of 25 hz, while the frequency of the secound source is 75 hx. waves from the first source have a wavelength of 6 m. they reflect from a barrier back into the original medium, with an...

I'm attempting to calculate the above, but I'm stuck. What I have thus far: intensity is the time average of the poynting vector, where the poynting vector is the cross product of the E and B fields. Using the given expressions, I get: \frac{\sqrt{a^2 + b^2}}{\mu \omega} E_0^2 \exp(-2bz)...

Hi all. First post and all that, so I hope I don't do anything wrong, and that if I do, you'll cut me a little slack :P Anyway, onto the question I'm wanting help with: A J-shock in a Herbig-Haro object is propagating through neutral hydrogen gas at speed 100km/s. The gas has number...

When light travels from a less optically dense medium to a more optically dense medium, the refracted ray bends toward the normal (i.e. air -> water). The reverse is true when traveling from a less optically dense medium to a more optically dense medium. Now... why is this? Why does a...

we have a non magnetic but anisotropic dielectric medium which has the following relationships between D and E Dx = k1*Ex, Dy = k2*Ey, Dz = k3*Ez we have to show that waves propogate in the z-dir'n at one speed only. I can't get the wave eq'n to fall out. Usually you just use...

In the text I use for class, the examples and derivations for functions showing the neutron flux at some point, are all about sources within infinite mediums. Now I have a probelm where I must show that neutron flux, for a point source within a finite sphere, is found by the following equation...

The information given is that a wave is sent though a wire with the frequency of 200 hz, and tarvles 500 m/s. A lighter witre is attached and the wave slows down to 400 m/s. Is it a higher or lighter medium? I want to say lighter as the wavelength is decreeased, meaning it has a figher...

I'm trying to create a model of the procedure of having a bone marrow biopsy done in order to seek ways of eliminating the pain which one has to endure during this process. I'll need to start with modeling fluid flow in a porous medium but this is something I've never done before and have never...

Through what medium does EM propagate in "empty" space? Einstein stated in his Leyden address (1926, I think) that an EM ether was mandatory for the transmission of EM waves through "empty" space. He was unable to reconcile this with the dynamical gravitational ether that had to exist to make...

When a ray of light travels from an optically denser medium to a rarer one such that the angle of incidence equals the critical angle, then the refracted ray grazes the interface. Now, will the principle of reversibility of light work in this case? If yes, please explain.

The fact that light has a smaller apparent speed in a transparent medium can be explained classically by considering the motion of the electrons of the medium in the oscillating (radiation) electric field produced by the source. Because they accelerate, these electrons emit an electric field...

How will it bend? Or will it not bend at all?

Second Postulate Of Special Relativity: "Speed of light in vacuum remains same for all inertial reference frames" The speed of light in glass is 2 x 10^8 m/s . So how is now the above postulate applicable?...Is it true that if one was sitting inside the glass slab , he would see the light's...

That is interesting ST. How dense is the inter-galactic-cluster medium? Garth

If current densities are given in a perfect dielectric medium having \epsilon , \mu I have to find the power dissipated per unit volume, the electric field energy density, and the magnetic field energy density everywhere. Can I get help with equations?

Ok, I don't want no equations and stuff please. :smile: When light travels through a medium the photons are absorbed by atoms in the medium and then a photon is given off by the atom of similar energy, etc, this is correct? If this is so does that mean when I look out the window that I'm...

Can anyone point me to some reference as to how magnetic fields are produced in the inter stella medium please.

How long can i store the mediums? Are the storage conditions the same for the medium of bacteria and mammalian cells? Thanks.

Velocity of light changes when it passes through a material medium. IS it possible for a particle(e. g. an electron) to travel faster than light in THAT medium? IF so, can someone give me some examples or experiments documenting this?

is there a website which shows which medium and serum is for a cell line (mammalian cells)? i have the problem looking for the right medium and serum. thank you.

new to the forums, had a question and thought someone might have an answer. If I remember from high school physics, in order for a wave to occur it must pass through a medium i.e.. sound through air, waves through water. my question is what do light waves use as there medium as they can travel...

Consider the electromagnetic field in a linear medium with material properties \epsilon \ \ \text{and} \ \ \mu . Calculate \nabla \cdot \mathbf{S} for the energy flux \mathbf{S = E \times H} . My work: \nabla \cdot \mathbf{S} = \nabla \cdot \frac{1}{\mu}(\mathbf{E \times B }) =...

I am trying to get a basic understanding of the physics of the interstellar medium and the current models which describe it (FGH and McKee-Ostriker). A first question arises regarding the possible assumption of a gas in ionization equilibrium, in which ionizarion and recombination occur at...

In audio, I've learned that sound energy are particles being compressed and rarified at specific rates, causing a "wave of pressure". Thus, sound is represented in a wavelength because of the medium it is "distorting" My barely-elementary understandinf of QED makes me believe that in order...

In this recent press release, "Chandra turns up the heat in the Milky Way center" http://www1.msfc.nasa.gov/news/news/releases/2004/04-169.html it is described the observation of heated gas at a temperature of 100 million K at the center of the Milky Way. It seams to be still an open...

Electrolysis will release the elementary components of a medium, albeit the process required a fare amount of energy, is there any other reasons it would be considered secondary to a more effience process? Does it have any pros?

Im not sure if this is the right forum for this question as I am unsure where it fits. I always think of a Shock Wave as something that travels through a medium, as in a sonic boom from an aircraft, but some talk of shock waves in space, as in the shock wave from a supernova, is this the...

Ok i thought i had this all set up but i can not configure my e mail i keep getting the error, fetchmail 6.2.5-45 i 586 was not found on the medium, do i have to load this from cd? once i found all the internet settings that worked ok without the cd. im using suse 9.1 thanks for any help.

Originally posted in College Level Homework help but I got no responses there. Please help if you can. I am studying for my qualifier and doing problems out of Jackson. I am stuck on this one... any help would really be appreciated... I am unsure how to begin: Jackson 7.15 The partially...

I guess I have rather a simple question: Can light be a medium for sound waves? I don't know where this question should be placed so I thought general physics was a good spot.

What comprises the transition from math to physics? alexander has said that physics is math. John Archibald Wheeler has wondered how equations "fly" (take on a physical character). I believe that math and physics are interchangable, that both can be shown to transform into the other. We...