Medium Definition and 390 Threads

Hi all. How does the speed of sound change with the medium? That is, how does it change with density, molar mass, temperature and in air, humidity. It seems that denser materials would increase the speed of sound, since the particles are more closely packed and therefore ease vibrations. The...

Why does light bend in a denser medium?

I know that a photon has no mass when it is traveling at the speed of light, however my question is, can a photon have mass when traveling through a medium, i.e. when its speed is less than c? I have done some reading but cannot find an answer. From this reading I have got the following: We...

i've been searching for the friction coefficient between medium carbon steels but can't find it, and also i see everywhere the yield stress of materials but i can't find the compressive stress of materials

Dear All, If two layers of thickness d1 and d2 stacked on each other and having their absolute refractive index n1 and n2 . Can we find effective refractive index of the combination with this data? Thanks in advance. Jayesh.

I wanted to ask the following question: If we change the medium of the wave (lighter or heavier) , how it will affect the particles velocity of the standing mechanical wave ? In my exam , there was a function's graph of one of the particles (of the standing wave) described with the...

Hello! I'm working on creating a sci-fi setting for a tactical space combat video game and short story series, and I had a few questions I couldn't find much info on after googling. I'll be playing a little bit loosely with the laws of physics for the sake of gameplay and storytelling, but I...

Homework Statement Two point charges, +4 μC and -10 μC are placed 10 cm apart in air. A dielectric slab of large area and thickness 5 cm is placed between the charges. Find the force of attraction between the charges, if the dielectric has a dielectric constant of 9. Homework Equations...

Hello Physics Forums! I've been educating myself on electrostatics, electronics, and electromagnetics and I have come to the topic of plasmas. I understand that plasmas are essentially charged gases - but their behavior is so disparate from regular gases that they are classified as the fourth...

Hello guys, I am a computer science PhD student. But my project somehow requires some knowledge about computational fluid dynamic modelling (both discrete and continuous). nowadays I am abit stucked in an issue. I want to model pressure drop across a filter medium dynamically. i assume i have...

Hi everyone, In my school I was given a problem. It's that Cr2O7-2 + H2S in a acidic medium. And my teacher told that Chromium becomes Cr+3 . I want to know is there such a way to calculate the oxidation number in acidic medium. Or is it required the experience?

I have a diode laser that emits multi-mode light. Two frequencies of this light are selected in an external cavity and reflected back into the laser diode. The laser diode's gain medium then resonate at these two frequencies and emits dual mode light. The laser operates in the 1550nm region...

Hi And Need Help The main Question is what happens to light and cause go into next medium as total internal reflection happens for incident angles higher than critical angle ? so the main question is why the light path throughout the second medium? We know when light travels from a medium...

Homework Statement Two small conducting spheres with radii a and b are imbedded in a medium of resistivity ρ and permittivity ε with their centers separated by a distance d >> a, b. What is the resistance R between them? Homework Equations R = V/I I = ∫JdS = (1/ρ)∫EdS The...

Yes holographs but not really So... I guess what I'm trying to get around is energy levels I will admit that my understanding is vague I believe I understand that certain gases are easier to excite (to give off light when going back down) like xenon but what about the general...

Is it possible to check the phase rotation sequence of a Medium Voltage Motor (Up to 6 kV) with one instrument? Does the shaft need to be moving while it is being tested? If instead of one, there are two motors electrically connected in parallel, with a common source feeder. will it be...

I've heard light compared to vibrations under the earth. The "waves" between the tectonic plates are simply a 'state', or 'action', i.e, the action of millions of atoms "bumping" into each other with their opposite charges (all the valence electrons repel other electrons). From my...

Does anyone know of a lasing medium (perferably something that can be doped into an optical fiber, but a liquid or gas would work if not) that has a strong absorption at 589.0nm and 589.6nm? Rationale: I'm trying to build a relatively cheap high powered (~300W-400W CW) LASER for DMLS, but...

Homework Statement Two Transverse Sinusoidal waves combine in a medium are described by the wave functions: y1 = 3sin∏(x + 0.600t) y2 = 3sin∏(x - 0.600t) what is y1 + y2? Homework Equations the hint is that I am supposed to use: sin(α + β) = sin(α)cos(β) + cos(α)sin(β) The Attempt at a...

1.I know this is a weird question, but does anyone know what the temperature of a bic lighter is after around 5 seconds? If left on for a minute? In my research I have come across so many different answers and was hoping to get a more concrete answer. Once I have the needed testing apparatus I...

what gives rise to eigenfrequencies?

At the microscale, an electromagnetic wave's phase speed is slowed in a material because the electric field creates a disturbance in the charges of each atom (primarily the electrons) proportional to the electric susceptibility of the medium. (Similarly, the magnetic field creates a disturbance...

Question: When an object travels through a certain resisting medium the deceleration is proportional to the 4th of the velocity. This, a = -kv^4. Prove v = u(ktu^3 + 1)^1/3 and subsequently x = (1/2ku^2)((ktu^3 + 1)^2/3 - 1). v at time 0 = u and x at time 0 = 0. Equations: Differentiation and...

Homework Statement Two point charges of magnitude q and 3q are located at a distance of 'a' from each other within an infinite dielectric medium of dielectric constant k. The force by the larger charge 3q, on the dielectric equals A)zero B)##\frac{1}{4\pi \epsilon_o}...

Hi! I have a high school physics question. I know the concept of induction, and I also know what happens when a dielectric slab is placed between 2 plates of a capacitor. 2 charged particles are kept at a distance r. The mutual force of attraction/repulsion is F. What happens to the force...

I know that light bends when traveling from one optical medium to another. The "classic" answer to this question is of course because the average velocity of light changes in the process. I've also seen other ways to make it "intuitive" enough to take it as a hard fact, eg. thinking of light as...

The speed of light in a vacuum is the universal constant c. The speed of light in a medium is something less than c; let's call it s. Has the positive difference (c-s) been observed as light travels through ordinary matter in space such as gaseous nebula or plasma nebula? If no, is it...

I have come to accept that the luminiferous aether does not exist. When we say that the electromagnetic wave is an oscillation of the electromagnetic field, then is not the electromagnetic field itself a medium that permeates all space? This is probably a dumb question, but I am as dumb as...

Homework Statement Homework Equations The Attempt at a Solution i have no clue about the second part..

Homework Statement https://www.physicsforums.com/attachment.php?attachmentid=57592&stc=1&d=1365348538 I'm stuck at the second part, not really sure what to here to be honest. https://www.physicsforums.com/attachment.php?attachmentid=57590&stc=1&d=1365346819Homework Equations Usually the...

Homework Statement Two point charges a distance d apart in free space exert a force of 1.4∗10^−4 [N]. When the free space is replaced by a homogeneous dielectric medium, the force become .9∗10^−4 [N]. What is the dielectric constant ϵr of the medium? Homework Equations E=F/Q The...

Hi All, I need help determining focal length value in a two lens system. In the set up, the light source (object) is within a tube, a medium surrounds it with refractive index n1=1.52. The end of the tube is met with a curved convergent surface, the center of which is 0.635 cm away and focal...

Homework Statement (see attachment) Given data: 1.The speed of light in empty space is ##3 \times 10^8 m/s##. 2.The mass of the proton is ##1.67 \times 10^{-27} kg## . 3.The speed of light in water is ##2.3 \times 10^8 m/s##. 4.When photon emission begins to occur the initial proton, the final...

I understand that light travels at “c” through any medium, and that the apparent slowing results from the absorption and re-emission of the photons by atoms in the medium. If this is the case, why, for example, are astronomers able to see the emission/absorption spectra of distant stars...

So I fully understand how alpha and beta can ionise different media. I also get why they can penetrate different media, but, what are the consequences (changes), if at all, to the media if after "absorbtion" or "penetration" a) What happens to a medium after radiation has passed through it...

This question is literally driving me crazy. How does the String or rope or whatever is used in a Foucault pendulum not twist with the rotation of the Earth (because the rope is attached to bases that are attached to the ground). Actually if the bases are attached to the ground, that should...

Hello everyone! I am sorry but i couldn't put this into the template. I am studying the spreading of a pulse as it propagates in a dispersive medium, from a well known book. My problem arise when i have to solve an expression. Firstly i begin considering that a 1-dim pulse can be written...

Hello everyone! I am studying the spreading of a pulse as it propagates in a dispersive medium, from a well known book. My problem arise when i have to solve an expression. Firstly i begin considering that a 1-dim pulse can be written as: u(x,t) = 1/2*1/√2∏* ∫A(k)*exp(ikx-iw(k)t) dk...

This I something I always wondered, but never could get my finger into: ##a_m = \frac{v_2-v_1}{t_2-t_1}## Alright, that's medium acceleration, but why isn't it: ##a_m = \frac{a_2-a_1}{t_2-t_1}## I mean, it does make perfect sense in my mind. Is it just because it was defined that way?

It is usually written that the speed of light in a dielectric medium is ##v=\frac{c}{\sqrt{\epsilon_r}}##, where ##c## is the speed of light in vacuum and ##\epsilon_r## is the relative permittivity. But, how can it be calculated for lossy and not necessarily low-loss dielectrics, i.e. those...

Homework Statement Hi everyone, As part of my final year project I am modelling the propagation of an electromagnetic wave through a medium of refractive index, n. I begin at the boundary between vacuum and the medium, x = 0 and propagate forward to some distance x. I have initially...

The title basically says it all, I'm wondering whether dark matter will allow sound to pass through because if it does, that could lead to being a way how to detect dark matter.

Hello! (I am sorry for probable mistakes. English is not my native language. I have never written anything about mathematics and physics in English.) I have an electrostatic problem. I need to find an electric potential \psi (\vec{E}=-\nabla\psi) in anisotropic, inhomogeneous medium...

In vacuum, the photon has a 4-momentum (E, p) with E^2 - p^2 = 0, i.e. it's massless. However, upon entering a medium of refractive index n, we expect that the photon retains its energy, while reducing its momentum by a factor n (due to increased wavelength). We then have for the 4-momentum of a...

Hello all . Can we consider space as a medium that photons and other waves travel on that ?

can nerves not be cultured in artificial medium? why? do nervers undergo cell division?

Deaar all good morning I am very interested to the flux in a slab of extrapolated thickness a, containing distributed sources of neutron. A I have an example in which the source is given as s(x)=S(x+a/2) where S is a constant and x distance from the center of the slab. You mentioned in one...

So I just wanted to clarify: Because D = ε0E + P P being zero in vacuum and ∇D is constant regardless of medium if D was originally in a vacuum, the corresponding E would be greater than if it were in an insulating medium. So, E in vacuum > E in medium

hello guys, i need your help to clear my concept on total internal reflection ...when incident ray angle is greater than the critical angle for light passing through denser to lighter medium the total internal reflection occurs...and i know about corresponding snell equation and its validity...

One of the main postulates of relativity is that the speed of light is always constant. However, light does not always travel at c, it only travels at that speed in a vacuum (supposedly). When it is in a medium such as water or air, it moves at a noticably slower rate, where even other objects...