Rays Definition and 315 Threads

What effect would a convex (concave) lens have on paraxial rays? For a convex lens, the rays would pass through and converge on the focus on the other side. For a concave lens, the rays would reflect back to the focus on the same side. Is this correct?

So i have a question regarding a homework question I'm working on which suggest a neutral pion traveling with velocity v decays into two gamma rays of equal theta to the normal and they of course have velocity c. It then asks to prove that v= cos theta Which kind of confuses me. I mean if...

Imagine two light rays parallel to each other , one of them is traveling in vacuum and the other one in water. We place a detector at the same distance from the source and fire the two rays inside their respective media.who will win the race? Or is it possible to have a tie in the competition?

Hello everyone. I was just curious if aluminum foil could block the sun's UVA rays. I have my home office and the sun always gets in and hits me. I know sunlight can cause early photoaging and cancers, so I want to block out as much UVA rays as possible. I do wear sunscreen, but I prefer...

I have been looking for information about the way Radiotherapy works and, needless to say, there is much more involved than just local frying of tissue. I have been told and also read, that the dose received in tissue is not necessarily maximum at the surface. For instance, the dose seems to be...

Homework Statement Let A, B and D be points. If ##D\notin \vec{AB}## in a metric geometry, prove that ##\vec{AD}\cap\vec{AB} = \{A\}.##2. Relevant definitions Ray: If A and B are distinct points then the ray from A toward B is the set ##\vec{AB} = \overline{AB} \cup \{ C \in P \ | \...

Homework Statement Why does an image form when light rays meet in ray optics? Is there explanation to it? Homework Equations The Attempt at a Solution I thought of an explanation myself and thought that it cannot be explained just like many other things cannot be explained like...

Why sun rays are not considerably hot when reaching earth..? is there any specific reason for the sun rays to lose its potential(temperature) as it travels a long distance in space where there is no forces to contain it nor disturb its motion. Does space have property too,because as far as i...

Hello everyone, I have some questions about these rays. And i would be grateful if you could help me, 1- The nature of cathode rays doesn't depend on neither the gas in the tube nor the material of the electrodes. Why? 2-The nature of canal rays depends on the gas in the tube. Why? 3-...

In the cathode ray production experiment, at about .01 mm of Hg, cathode rays travel from cathode and move towards anode and produce fluorescence on the walls near the anode.At the same time canal rays also move towards cathode. But only when you use a perforated cathode, the canal rays...

Hello, I was doing a little research on nanotubes and came up with an idea. If we shot a cylindrical beam of electrons a few nanometers apart from each other and then shot a carbon plasma down the center would the carbon atoms be attracted to the electrons and form a nanotube at a sizable scale?

I've heard of cosmic rays affecting measurements made at the LHC in the context of muons. Is it just muons that can reach the detectors or is there background from other particles as well? Why are muons a background but not electrons? How significant is it? Thanks.

Bee Hossenfelder has an interesting post I'd like to get some comment on http://backreaction.blogspot.com/2013/07/more-mysteries-in-cosmic-rays-and.html More mysteries in cosmic rays, and a proposed solution "...One mystery we already discussed previously. The “penetration depth” of the...

If the sun is producing plasma on a large scale on a regular basis, isn't it then true on a smaller scale that we could use the UV Rays of the sun to produce plasma by smashing two magnified rays and liquid hydrogen together in a high speed chamber? The result would be hot plasma that could be...

This problem is about seismic wave propagation in a non-homogeneous layer over a halfspace. I'm not asking you to solve anything, I've already solved the problem both algebraically and in Matlab. However, the graph that I've gotten mildy surprises me. According to the graph, the seismic rays...

If what used to be visible light when the universe was smaller and younger has been stretched due to the Doppler effect so that it is now microwaves and detectable as the Cosmic Microwave Background Radiation that can be found everywhere, why hasn't the gamma or x-rays of the same period not...

As we know, Bragg's law is based on the path length difference between light which interfere with themselves after being scattered from atoms in the crystal. If you google "Bragg's law", you will see numbers of pictures showing two light rays being scattered from two different atoms. Those...

I am wondering, what is the dimension of a ray in a Hilbert space? For example here (page 2, bottom of page) I have read: I understand why a state is represented by all multiples of a vector, not just the vector. But is the ray really one-dimensional? It would be one-dimensional if we multiply...

Homework Statement Consider Schwarzschild spacetime. A) Show that the equation for ingoing/outgoing radial light rays is dt/dr = +-r/(r-2m) in t,r coordinates and dt*/dr = -1, dt*/dr=(r+2m)/(r-2m) in t*,r coordinates B) Sketch the local light cones in t,r and t*,r coordinates C) Explain...

Homework Statement Draw the ray diagrams for a pencil sitting on the principal axis behind and in front of the focal point of a converging lens. Describe the image. Do the same for a pencil sitting on the parallel axis behind and in front of the focal point of a diverging lens.

Homework Statement This is one of my homework questions. I think I have the right answer, but I don't understand how to figure out the "given" angle, so if someone could explain it to me, that would be great! Be sure to look at the picture attached...it's what's tricking me. A prism...

Hi all, I think this question goes best in this section, because I think the answer is something a nuclear or particle scientist could answer. In space, what would happen to a ship that did not have proper shielding from cosmic rays? (NOT the astronauts themselves; there is plenty of...

Homework Statement Let us assume that ray XY is a limiting parallel to line l, with P*X*Y. Prove that ray PY is a limiting parallel to line l. Homework Equations Steps will go something like this: Show that ray PZ meets line lat a point V. Pick a point S such that P is between S and...

Hello everyone. I'm looking through an old book on optics and something there has me really confused. I attached the two pages I'm referring to, or you can find them here: http://www.maths.tcd.ie/pub/HistMath/People/Hamilton/Rays/ as pages 14 and 15 in the pdf. Basically, what's going on is...

But high frequency are absorbed, like gamma rays. I would think it would be the opposite. So what's the physical reason?

hello I have a question: i am trying to understand how we find out that the curvature of the universe is zero using the angular size of the hot spots of the d microwave background radiation. http://scienceblogs.com/startswithabang/2012/07/18/how-big-is-the-entire-universe/ there is a...

1. I have problems finding the truth of this statement. The statement is cited from "book". I want to draw your attention to the following words: electron is decelerated 2. Statement: "Bremsstrahlung X rays result from Coulomb interaction between the incident electron and the nuclei of the...

why current does not flow through gas in discharge tube at ordinary pressure?

Hello, I'm trying to figure out how to calculate how much energy is being released in a nuclear fusion reaction from x rays. I think it will have to do with how much deuterium is in the vacuum chamber, how many volts I am using and the amount of resistance of the mesh the electricity is...

Or light rays for that matter. Where does the window open in the atmosphere on the em spectrum, UV? Why is that?

Homework Statement Calculate the minimum energy of a cosmic ray that it needs to have in order to "point" back to its origin. Let's define this as being deflected by the Galactic magnetic field of B = 1μG by less than 1°, as it traverses a distance of d = 1 kpc within the Galaxy. Calculate...

The advocators of Darwin’s theory of evolution discover that it is difficult for normal evolution rate alone to form the species diversity now. What factor(s) accelerated the origin of life and species diversity? Reference viewpoints: Novae, especially supernovae, would generate high energy...

Making it short : Do gamma rays ALWAYS accompany a nuclear reaction?? I was thinking, since there are only three types of radioactive decay, alpha, beta and gamma. I don't quite understand how gamma radiation will always occur. Isn't it going to be just ONE of the three types? /Help :)

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 detector is used to count the number of gamma rays from a radioactive source if the number of counts is 10000 in exactly 20 secs then what is the error in counting rate per sec? Homework Equations- no idea. The Attempt at a Solution- As per our syllabus we...

During discharge tube experiment, the cathode rays are emitted from cathode at very low pressure...it is said that these rays move at very high velocity(if we apply high Potential Difference between 2 electrodes)...do these rays( stream of electrons) travel in uniform velocity or aren't they...

Hello, I am trying to simulate the gammas from certain radioactive decays but I am really puzzle as to how to approach this. The site I'm using as a reference lists the intensities of the different gammas corresponding to an specific decay. The thing that confuses me is that, for example...

Light requires some medium to pass through, what's the medium in the space, and How does sunrays enters into the earth.

Would it be possible to produce a fusion reaction(fusing deterium atoms) using x rays instead of high voltages? Scientist are trying to create fusion using laser, which is just focused photons, but if you have energetic photons such as x rays, which would knock the electron of the deterium atom...

I know we can contain the energy/plasma from a fussion reaction with an electromagnetic field, but would an EMF protect from gamma rays? Would it be possible to deflect a nuclear blast with a powerful enough EMF?

Good afternoon friends, I was wondering, "if the visible radiations coming from sun get charged say positively charged, then what will happen?" I am sure that most of its part will not reach the ground but some. But can we obtain the location of black zones for the radiation? Is it possible...

The Reference Frame: A confirmation of the 130 GeV dark matter-like bump - Lubos Motl [1204.2797] A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope - Christoph Weniger [1205.1045] Fermi 130 GeV gamma-ray excess and dark matter annihilation in...

Why are cathode rays able to penetrate very thin metal films?

How can we safe us from ultraviolet rays? Guide me which diseases caused by ultraviolet rays?

Hello, Would you know a reference showing and deriving the equations of light rays in GR. I would like to read that as well as to compare that to the equations of motion of test particles in a gravitaional field. Thanks, Michel

Homework Statement Calculate the angle between the ray PQ and the ray RS Anouther ray TQ also strikes the surface at Q. The refractive index of the glass is 1.50 Homework Equations c= 1/ refractive index The Attempt at a Solution The answer on my sheet say it is 20 degree, I...

I want to know if there is magnetic field around a cathode ray tube. That is, does magnetic compass deflect when brought close to a CRT ? If so, can this magnetic field (produced by cathode rays) be used to have Lorentz force on a moving charge particle ? Presently, what I think is...

Hi all, I was having trouble with this problem and hoping that someone could help me with it. A pion has a rest energy of 135 MeV. It decays into two gamma rays, bursts of electro magnetic radiation that travel at the speed of light. A pion moving through the laboratory at v = 0.97c decays...

Homework Statement Given is the X-ray machine in which electrons are accelerated in the potential difference of 10000 V before hitting the electrode and loosing its energy. Find the maximum energy of the emitted X rays in keV and in Joules. Homework Equations The Attempt at a...

Homework Statement Using a 1 electron model, evaluate the energies of the muonic K X rays in Fe assuming a point nucleus. Homework Equations The \Delta E is the difference between energy of the 1s state in an atom with a "point" nucleus and the 1s energy in an atom with uniformly charged...