Rays Definition and 315 Threads

Homework Statement An electron and a positron are moving side by side in the +x direction at 0.50c when they annihilate each other creating two gamma rays. What is the energy of each photon? Homework Equations (mc2 + K+) + (mc2 + K-) = E1 + E2 The Attempt at a Solution I solved...

^ thanks

Does skin that is perpendicular to the sun’s rays burns faster than skin that is closer to parallel to the sun’s rays? I was certain that it does but a very smart friend/engineer is certain that it doesn’t and was incredulous that I thought it did. I really would like to know the physics...

Hello all, i am having a few problems simulating cosmic rays with a silicon CCD detector, mainly because my knowledge on particle physics is quite poor. I am simulating primary cosmic rays, which predominantly consist of single protons and alpha particles. I am treating the protons...

In Kip Thorne's BLACK HOLES AND TIME WARPS,1993, he mentioned on page 173 that some cosmic rays particles are made of antimatter..and this was discovered by Carl Anderson at Caltech...seems like in the early 1930's... I could not find anything about antimatter Cosmic Rays in Wikipedia...

It's simply common sense that looking directly into the sun is a bad thing, but what about with your eyes shut? I'm unsure if the UV rays can penetrate the eyelid, or at least if they can, if a significant percentage of the rays get through. Is it a factor to consider when tanning for over an...

Homework Statement Parallel light rays travel from air towards a glass hemisphere with radius R and index of refraction ng > nair. A top view is shown in the figure. http://img8.imageshack.us/img8/6380/parallellightrays.jpg (a) Determine where the light rays come to a focus relative to the...

Homework Statement A light ray with direction (1, 2, -2) passes through the point (-1, -3, 5) and is reflected farther away on a plane. The reflected ray has the direction (3, 0, 4) and passes through the point (4, 1, 5). Determine the equation for the plane which reflects the ray. The...

Homework Statement A gamma ray from 198Au incident normally on a thick aluminum slab travels 1.45 cm before it undergoes a Compton scattering. Calculate the range of angles through which the gamma could scatter and still have at least a 10% probability of re-emerging from the incident slab...

Hi guys, me again, with two questions. Just saw a documentation about supernova, when supernova happens, a huge amount of gamma ray is emitted since it is vacuum in space, why wouldn't the gamma ray hit us? Even if its far and takes a few thousand years for it to reach us, it would eventually...

Does anyone know the speed that gamma rays travel, as a speed or in proportion to the speed of light. Thanks

Short question. I know that COLLIDING beams are much more effective than when moving particle hits a target in observers reference frame. That is why they make a collider. However, when Oh My God particles are observed they actually hit something that something does not move. So, when...

Hello everyone, Quick questions What happens to the light ray that passes through the mid point of the lens(dotted line). Does it go straight or diverge? Is moon concave? If the light passes right through the midpoint travel straight wouldn't the umbra have some light in the...

which color is better at blocking UV rays? my take on it is this analogy: you have a room with one window, cover it with a fabric curtain that is black the room becomes very dark. cover it with that same curtain except white and the room is somewhat brighter. less light = less UV rays a...

Hello PF members, I curious to know some basic idea..why the line shape of nuclear decay is displayed as a Breit-Wigner (BW) profile (x-axis as energy and y-axis as intensity) ??.. or any \gamma ray is often shown as a BW profile?? thanks for your reply.

This is a physics and math problem The representation of a vector as a straight ray is problematic Imagine an arc of a circle formed as a result of uniform circular motion.In time Δt, it traces out an arc of length vΔθ such that vΔθ/Δt =vω is the acceleration. v=rω comes from the fact that...

I know that a Hypernova release two huge jets of gamma rays, but I'm not real sure on how they are formed. Also it was mentioned that by following the burst of gamma rays, we're looking back in time. How is this actually possible. I have a shaky grasp on the idea.

Im trying to find the number of delta rays though a material and am having some trouble with the units, can anyone help? The number of delta rays through a material is given by N=epsilon(1/E1 - 1/Emax), where epsilon=[2*Pi*A^2*e^4*ne*x]/[m*c^2], where A is unitless, [ne]=cm^-3, and the...

Hi there! The experiment: I'm counting Gamma and beta rays emitted from gamma and beta cylindrical sources, for counting I'm using a simple GM counter, which has nearly the same cylindrical shape (i mean diameter). As we all know this are electromagnetic emissions, so they distance must...

Assume I am standing in a desert at night (It's pitch dark). I have an opaque white object in front of me inclined at 45 degrees (see diagram). I now turn on a point light source next to me. http://img199.imageshack.us/img199/8945/lightt.jpg When I imagine the scene I feel I will be able to...

I need to know the practical applications of the absorption of gamma rays in materials.

I've read that some protons in the Universe can have an energy of about 10^{20}eV, or in English, about a well-hit tennis ball. (The cosmic rays). Is it possible for these rays to reach our brain? Or more precisely, what would happen if one gets hit by such an energetic particle? P.S.: I...

Is there any on-line reference which describes the interaction of high energy (> 100 Mev) gamma rays with matter. These are gamma rays from gamma ray bursts, etc. in contrast to low energy from nuclear radiation.

Hello, I am reading Weinberg's book and in the part on symmetries he speaks about rays, and says basically that 2 vectors U,V which are on the same ray can only differ by a phase factor \phi, so that U=e^{i\phi}V. Is "ray" meaning "direction" here ? Can I rephrase it and say that 2...

Assume that it hits the Galactic magnetic field at an angle of 45o, i.e. such that the components of its momentum parallel and perpendicular to the magnetic field are equal. What is its cyclotron radius? How long does it take to execute one cyclotron orbit? W ealso, know velocity From part...

Dose the cosmic rays have any roll in our weather This question hits me yesterday when I was studying the electric charge and its roll in the weather , so dose the cosmic rays have any roll or its roll is just negligible…. when they hit our atmosphere

I remember reading before that hydrogen gas is "transparent" to gamma rays. What does this mean? I know it has something to do with the gamma rays not heating the hydrogen. Also, would Xenon gas be transparent to gamma rays?

QUESTION: Astronomers observed the interference between a radio wave arriving at their antenna directly from the Sun, and on a path involving reflection from the surface of the sea. (http://i62.photobucket.com/albums/h101/kaikibana/problem1.jpg) Assume that the radio waves have a frequency...

We were discussing in an https://www.physicsforums.com/showthread.php?t=284322" that pinholes work like lenses, in that they form inverted real images. The other day, a friend told me, that pinholes even do bend the light rays like a lens do. I can - as being nearsighted - actually use a pinhole...

I am a new product development engineer and am working on figuring out a UV sanitization product. Do you know of a good resource to understand UV rays, its properties, using UV, etc.? I am not looking for detailed math models and analysis, but rather, a resource that will help me...

I know the process of their production, now I want to know what's their origin? How does an atom produce them? PS:Donno whether it's the right forum to ask this question or not, so feel free to move it to the right place!:smile:

Recently on nasa's site: http://science.nasa.gov/headlines/y2008/19nov_cosmicrays.htm My question is...has there been any studies since 2004 to show the link between galactic cosmic rays, and cloud formation, and/or changes in cloud forming bacteria and/or the effect these have on the...

Homework Statement So anyway in the diagram of my book there is a ray hitting the centre in the flat part of a semi circular prism. The question in the book states "Ignoring partial reflection, we know that each ray will pass through the flat surface and then pass through the curved surface...

I am trying to calculate the strength of the magnetic field ( in teslas ) that would be needed to deflect cosmic rays going about 99% the speed of light. using the lorents force http://en.wikipedia.org/wiki/Lorentz_force I replaced force with mass times acceleration I canceled...

Im having problems understanding headings for 3d rays. I mean with 2D you can have an object at (2,3) with a heading of 83 degrees. But in 3d you can have an object at (2,3,3) but how can you describe its heading, do you need two separate headings for the two planes, how does this work. Thanks...

http://www.nytimes.com/2008/10/28/science/28xray.html?ref=science I don't know why but I found this to be amusing. It sounds like something from the Onion, or our own Turnip...hey whatever happened to the Turnip thread.

What damage to the body can infrared rays, radar waves, FM waves, TV waves, "shortwav What damage to the body can infrared rays, radar waves, FM waves, TV waves, "shortwave" waves, and AM waves do? I have to do a physics project on causes of cancer, based on a physics standpoint. I have an...

what's the difference between gamma rays and x rays?

Problem: Diffraction of X rays has been observed when a beam strikes an extremely fine slit. What must be the width if the slit if X rays of wavelength 10A are to display a diffraction pattern with a central beam of angular width 0.1? I used Bragg's equation to obtain...

Homework Statement let there be three points: A, B, and D. Light of wavelength 400 m is emitted from the source at A to the destination D, and also from B to D. Line segment AD is 100 m longer than BD. The starting phase of the light at A is pi/2 radians ahead of B. At point D, what is the...

http://www.sciencedaily.com/releases/2002/10/021031071017.htm ScienceDaily (Oct. 31, 2002) — WASHINGTON - Researchers have found that a portion of anomalous cosmic rays -- charged particles accelerated to enormous energies by the solar wind -- results from interactions with dust grains from a...

http://en.wikipedia.org/wiki/Cosmic_ray I have a little bit of trouble writing an essay that relies on background knowledge of galactic cosmic rays. I found in textbooks solid writing about the history of discovery and composition, etc. I can not find simple exemplary nuclear reactions...

Homework Statement see topic title Homework Equations I think that sound waves are vibrations of particles in a medium. The vibrations continue until the energy is gone. Sound seems to need a medium to travel through. Light can travel in a vacuum. your eye sees it from a source...

Hello everybody, actually yesterday i read about an experiment "ATTENUATION OF GAMMA RAYS". can anybody tell me what is meanning of word ATTENUATION.And why we are measuring it? i.e. what is the sigificance of measuring it?

Can someone tell me how much does a light ray bend when it passes over the surface of the densest star known? Is it like 1 degree, or more like 30 degrees? Please leave out black holes, this question is about normal stars, the densest one that is known. Is Sirius the densest normal star...

Homework Statement Self-Reproducing Rays in a symmetric Resonator. Consider a symmetric resonator using two concave mirrors of radii R separated by a distance d=3|R|/2. After how many round trips through the resonator will a ray retrace its path? Homework Equations The Attempt at...

What is the physical process common to both the emissions of atomic x rays and nuclear gamma rays? is it photoelectric.. or the inverse.

A person being exposed to radiation (restricted to gamma) can have a time dependent effects. One can die in a year, months, or even days depending on the dose. Is it possible that gammas can kill a person almost instantly?

hey guys i really need help with these problems.I am not good with physics at all, i just need this to graduate . I really don't understand it and my teacher isn't much help. If anyone can help me out with this i would really appericiate it. Thank you. 1.Why are parallel light rays used to...

hey guys i really need help with these problems.I am not good with physics at all, i just need this to graduate . I really don't understand it and my teacher isn't much help. If anyone can help me out with this i would really appericiate it. Thank you. 1.Why are parallel light rays used to...