Ray Definition and 517 Threads

I'm studying wave propagation in the ionosphere, which can be modeled as a dielectric that has a magnetic field present. My understanding of it is that the Poynting vector that is associated with the wave in the medium is not generally in the same direction as the k vector (what I understand to...

If a gamma ray is being fired and is in turn colliding with electrons and ionizing the electrons in the gamma ray path, where do the electrons tend to? In what direction is the current most likely to flow for a high powered gamma ray ionization?

Homework Statement A light ray parallel to the x-axis strikes the outer reflecting surface of a sphere at a point (2,2,0). Its center is at the point (0,0,-1). The unit vector along the direction of reflected ray is ##x\hat{i}+y\hat{j}+z\hat{k}##. Find the value of ##yz/x^2##. Homework...

i have a doubt in this problem ; is correct say that : L_m(y) = L(y) + δL(y) = L(y + δy)= L(y) + δy(∂L/∂y) ?? where L_m is modified Lagrangian and y is dynamical variables. I get answer but i have it doubt.

Does the light ray that had hitted a body carry the information about the body that it has hitted? Because when we see our own image in a mirror the image is same as of us. so do the photons of light carry information about the part from which they are reflected? thanx

Homework Statement An astronomical telescope is constructed using 2 convex lenses. The objective lens is of focal length 40cm and eyepiece lens is of focal length 10cm. Let d be the distance between the 2 lenses. Draw ray diagrams for the following situations. 1.When d=50cm 2.When d>50cm...

Can you advise me a free software that allow to draw rays passed throught system of thick lenses (preferable in 3D)?

I can't get the concept why there is no diffraction when lambda tends to 0 even for extremely small aperture.please explain simply.

http://www.bbc.co.uk/news/entertainment-arts-22441567 One of his best:

I have read articles about the GRB measurement using X-ray from afterglow. The article tells that the gamma ray provides poor directional information.Why? How can we use X-ray for measurement?

Homework Statement Part a) Deflection of the electron beam in a cathode ray tube television set has electrons accelerated until they have K.E. of 25 keV. What is the magnetic field magnitude required to deflect the electron beam 3.3 cm when the magnetic field is 8 cm long? Part b) When...

Hi guys, I'm constantly bothered by one assumption in my textbook..it says that the photon emitted by the accelerating electron boiled off from the cathode colliding into the anode, has E=hf neglecting the work function, since its negligible. I'm curious whether it's E=hf plus or minus the work...

I have been doing many experiments with light and magnetism, and one of the things I noticed is that when light is passed on the right side of a sphere (e.g.) some of the laser rays will deflect from a straight path and bent towards the left. I believe this is known as the "creeping ray"...

Hey guys, So some friends and I are studying for a test and we came across this question. I've absolutely no idea what the answer is simply because every website I've found only shows parallel rays and a ray going through the centre of the lens. It's incredibly aggravating. Anyway here's the...

http://global.britannica.com/EBchecked/topic/495677/refractive-index refractive index, also called index of refraction, measure of the bending of a ray of light when passing from one medium into another. If i is the angle of incidence of a ray in vacuum (angle between the incoming ray and the...

1. A ray of light passes from air through dense flint glass and then back into air. The angle of incidence on the first glass surface is 63.5°. The thickness of the glass is 4.26 mm; its front and back surfaces are parallel. How far is the ray displaced as a result of traveling through the...

Hi friends, Please help me in answering this problem The problem is as follows, https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-prn1/s480x480/11130_2937865262994_1085043361_n.jpg Well, Friends when the lower mirror would be at position 'A', which is moving in the upward direction...

Hi friends, Please help me in answering this problem The problem is as follows, https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash3/s480x480/557923_2937818221818_1718139220_n.jpg Well, As far as I am concerned, When white light fall on the first surface, after refraction...

can proton particle like alpha particle travel as rays in space?if yes, how are this rays produced in nature and artificially by man?

Pretty much what the title says. Suppose we have a topological vector space $(X,\tau)$ and $U\subseteq X$ is topologically bounded. Is it possible for there to be some $x\in X$ such that $cx\in U$ for arbitrarily large $c$? I'm thinking of a real vector space here. If we try to prove...

Hello, why if a ray pass though different materials its direction changes ? couldn't its propagation speed just increase or decrease without having to change the angle ? Thank you

If cosmic rays include particles with energies way way beyond what is achievable with classic colliders like the Tevatron and LHC, why not build light collision detectors and have them carried aloft. AFAIK altitudes of 20km-50km are possible with present high-altitude balloon technology. At such...

I'd like to know why a ray of light passing through the optical center of a convex lens does not get refracted at all. According to my knowledge, a ray of light will not get refracted if the angle of incidence is zero i.e. it is along the normal. With this in mind, I see how a ray traveling...

In a continuous isotropic medium having refractive index n, (not constant) the ray path can be described by the following equation d/ds(n dr/ds)) = grad (n) with an obvious meaning of the symbols (for they who can help me!). I wrote a code to calculate the ray path. I found result...

Homework Statement A 1.0-cm-tall object is placed 4.0cm from a diverging lens of focal length 6.0cm. Using both ray tracing and the thin lens formula, find the location and orientation of the image. Homework Equations -1/f = 1/so + 1/si m = -si/so = hi/ho The Attempt at a Solution...

Homework Statement A light ray passes downward into a block of transparent plastic with an angle of incidence of θ1 = 77.7°. If total internal reflection is to occur when the light strikes the left edge of the block at interface B, what is the index of refraction of the plastic? Homework...

http://arxiv.org/abs/1206.1616 Strong Evidence for Gamma-ray Line Emission from the Inner Galaxy - Meng Su, Douglas P. Finkbeiner Analysis of data from the Fermi telescope shows "monochromatic" gamma ray emission at 130 GeV from the centre of the galaxy. This paper is generating a lot...

Hi guys, I cannot understand why we need to correct cosray intensity with pressure and why the equation that describes the phenomenon is I=Io*exp(-a(Δp))? I want to know the phsyical meaning of this(i assume,experimental) result... Thank you...

A ray of light is coming along the line $y=b$,($b>0$), from the positive direction of the x-axis and strikes a concave mirror whose intersection with the $x-y$ plane is the parabola $y^2 = 4ax$,($a>0$). Find the equation of the reflected ray and show that it passes through the focus of the parabola.

According to Wikipedia: The part I don't understand is why all rays that are sagittal rays that are not the chief/principal rays must be skew. Do they just mean all other rays originating from the same object point must be skew? Because that makes sense. Are these things always discussed...

Hello there. I am wondering if anyone can shed some light on this topic. I am searching all over the Internet to find reliable sources on the possibility of gamma ray lasers. I know that it requires an atom that can be "pumped" without spontaneously emitting its energy so it can be triggered by...

what do u mean by gamma ray branching ratio of 'k-40' is 10.67%?

Homework Statement A radioactive source which is known to emit gamma rays only at a single energy is placed in front of a gamma ray detector. The gamma ray pulse height spectrum shows three distinct pulse heights of 7.38,6.49 and 5.60 volts. What is the energy of the gamma ray? The Attempt...

I’m curious, but no mathematician. Euclidean geometry is the only type for which I've had training (45 years ago). Apologies in advance for misused terms. A line, as I recall, extends indefinitely in opposite directions. It has no definite “origin” or "center". If we view “translational...

Has anybody thought of it before? I mean even if it were energetically expensive to harness it it might actually create more than it takes since the energy source is raining down from the heavens anyway. Such a power plant would have to be placed at a high altitude though because most cosmic...

Homework Statement I have to figure how many beta particles are released and how much energy is released as gamma rays in the complete decay of 1000 atoms of (12/5) Boron. Homework Equations Mass of one boron atom is 10.811 g. I think we may be able to use E = mc^2 somehow but I'm not sure...

The question can be found at this link: http://gyazo.com/ee82873af32d76898ab1c5b9f058a2eb My reasoning for part A follows as such: Because the radius of curvature is smaller in the second mirror than in the initial elliptical mirror, every point on the second mirror (other than the tangent...

Hi, I have a rather basic question: most 'cosmic rays' have an energy of about 109 eV, but there are also 'Ultra-high-energy cosmic rays' with an energy of around 1019 eV to 1020 eV, so I was wondering if they couldn't be the result of collisions of two 'normal' cosmic rays that hit each...

Homework Statement A beam of gamma rays of energy 1.00 MeV are aimed at a set of freely moving gold particles. The gamma rays reflected back have an energy of 0.2035 MeV. How is this result consistent with the model of a gamma ray reflecting from an isolated electron initially at rest...

Homework Statement The problem I am having troubles with is proving the deflection of a ray by a prism can be represented by a specific equation : θd = θ - α + arcsin(sin(α)√(n2 - sin2(α)) - sin(α)cos(α)). I have derived another form of the deflection equation for a prism and I am attempting...

I was in my AP Physics class discussing wavelengths of the electromagnetic spectrum and I came up with the idea to attempt a gamma ray microscope. Of course this is extremely dangerous, so I will have to be cautious (and use a lot of lead). Is there a way to produce gamma rays? I know they...

I have some basic doubts in the alpha ray scattering experiment by Rutherford and his students way back in 1909. 1.In the formula for the distance of the closest approach, the term velocity of the alpha particle and the charge of the gold nucleus appears. How did they measure the velocity of...

Last month my sister and I were driving down a Maine highway to visit relatives up North. As we were chatting, I saw a perfectly straight, narrow, luminous line appear momentarily in front of the tree line (on the order of 100 meters away). It lasted just long enough to see and then it was...

In a video demonstration (not animation), cathode rays appear as a beam of green light moving from the cathode to anode inside the tube. The demonstrator brings a magnet near the tube and the green beam deflects. This I can understand. What I can not understand is that how the electron beam...

It appears that our resident ray of sunshine is missing in action or absent without leave. Last seen online a day and a half now, while she seemed never to be offline before. We noticed this: Anybody have more info? :confused:

In descriptions of the cathode ray, various sites mention how the ray is formed from a voltage applied to the tube which spawns the ray on sees in the vacuum tube. Could someone elaborate on how a voltage can spawn this beam? As in, where does the potential difference come from and so on...

I'm interested in calculating how much power (in Watts) could be produced (assuming a 100% conversion efficiency between Gamma Rays and electrical power) from gamma decay of a 60 Co -> 60 Ni. How long would this reaction last? Just a few seconds or longer? Are there any decays that last for a...

In the hunt for antimatter galaxies, the tools that we are currently using look for gamma rays that would be emitted due to annihilation events, because everything else about these galaxies is predicted to be the same emission-wise. The hypothesis is that these annihilation events would occur...

So, if my understanding of GRBs is correct, they are a collimated jet of material that produces a lot of gamma rays. So my question is, don't these have to be pointing right at us for us to see them? If so, then why do we see so many? I think it's at around at least one per day, the last time...

When I was a youngster, "The Martian Chronicles", "The Illustrated Man", and "Fahrenheit 451" were all required reading for us nerdy types. RIP, Mr Bradbury! http://www.reuters.com/article/2012/06/06/entertainment-us-usa-bradbury-idUSBRE8550UC20120606