Quantum physics Definition and 728 Threads

Hi, Can you help me with this, I don't know how to go about solving this. Question:

http://www.higgo.com/quantum/modest.htm"

An electron with kinetic energy E=2.0eV, is incident on a potential barrier with V0=6.5eV and width 0.5nm. What is the possibility of the electron tunneling through the barrier? If a pulse of 1 million such electrons incident on the same barrier, how many electrons can be detected in the other...

I have an infinite potential well with length L. The first task was to calculate the eigenvalues and -functions for the energy of a particle in the well. The requirements were \psi(0, L) = 0 and there is no time-dependence. I've calculated: \hat{H}\psi(x) = E\psi(x) E =...

Homework Statement suppose V(x) is complex, obtain an expression for ∂/∂t P(x,t) and d/dt ∫-∞∞dxP(x,t) for absorption of particles the last quantity must be negative (since particles disappear, the probability of their being anywhere decreases). What does this tell us about the...

I know that quantum physics is the physics of subatomic particles and that it has lots of "wierd" topics but what is the proof behind it and where sould i start to learn quantum physics? I've taken physics and studyed mechanics, therodynamics, viberations and waves, magnetism, optics and...

Homework Statement this problem is from (chapter 2 problem 1, gasiorowicz, quantum physics) where I am given A(k) = N/(k2+a2) and must calculate psi(x) Homework Equations I am using the equation psi(x,t) = integral from - infinity to + infinity A(k) ei(kx-wt) dk which when...

Homework Statement integral from - infinity to + infinity of N/(k2+a2) * eikx dk Homework Equations this is for a quantum physics problem (chapter 2 problem 1, gasiorowicz) where I am given A(k) = N/(k2+a2) and must calculate psi(x) I am using the equation psi(x,t) =...

Uniting quantum physics with the theory of relativity is not possible. What are the problems / challenge?

In Volume II Chapter 19 of his Lectures on Physics, Feynman discusses the principle of least action and its role in quantum mechanics. He says the following on page 19-9: "The complete quantum mechanics (for the nonrelativistic case and neglecting electron spin) works as follows: The...

Hi. Would you guys think it is essential to take a course or read a book based on classical physics as a starter leading on to quantum physics? I got a pretty deep book on QP but the maths has got me lost because it takes a lot of stuff from classical physics and not having been in a maths...

Hi everyone. Does anyone know any good books (easy to understand, not too lengthy) on quantum physics. Right now, I am studying aerospace engineering (2nd Year) and honestly, I have always loved physics...but right now, studying higher physics is kinda hard for me given the degree I am doing. I...

I was wondering if someone could tell me what exactly is the difference between Quantum Chemistry and Quantum Physics? Whenever I look in a Chemistry textbook, I see Quantum Chemistry and the latter is true for Physics - yet strangely enough I see most of the information is quite similar...

Can anyone recommend a beginners book on QP that is academic in nature? I've just about finished Quantum Physics: a beginners guide. I found that it skimmed a lot information and the equations were not fully explained. Thanks :) First post :)

This should be easy, since I'm sure I've misunderstood something here. The task is to find the commutator of the x- and y-components of the angular momentum operator. This operator is, according to physics handbook: -i \hbar \bold r \times \nabla I rewrote this as: i \hbar \nabla \times \bold...

Hi everyone, first of all let me state I'm no expert in quantum physics. But I'd be glad if any of you would just introduce a little to how temperature is understood from the quantum model stand point. From a classical point of view I believe temperature is a measure of the internal energy of an...

When considering a simple hydrogen atom, which essentially is an electron moving in a spherical electric field, you don't need to take spin-orbit coupling into account. For larger atoms you do. I don't understand my books' very brief explanation of this. I am thinking that the electron has as...

Homework Statement The X-ray spectrum for a typical metal is shown in Figure 31-22. Find the approximate wavelength of Kbeta X-rays emitted by titanium. (Hint: An electron in the M shell is shielded from the nucleus by the single electron in the K shell, plus all the electrons in the L shell.)...

i) What is the energy required to singly ionise a ground state Helium atom into the first excited state of the helium ion? ii) What is the energy required to excite a ground state helium atom into the first excited state of neutral helium? iii) What is the energy required to doubly excite...

I own a Sony PSP, and am curious as to how it works on a quantum level, from knowing what part the electrons in the circuit board work to what part the photons play in me being able to see what's displayed on the screen.

Hi, everyone. I'm not sure if this is the right forum as this isn't a simple question-and-answer homework assignment, so please excuse me if this isn't in the right place. I posted this in a different forum earlier and I think it got deleted, so apologies for the double posting. I'm a high...

[SOLVED] Silly Quantum Physics questions I'm afraid to say that I have a test in my undergraduate Quantum Physics course tomorrow. I feel prepared for the most part - but I am trying to tie everything we're learning together. In hopes of doing this, I have a couple questions that I would like...

The professor of my undergrad quantum course said that I could get some extra credit if I did some sort of outside project and presented it to the class (for example, for my E&M Professor I built a Tesla Coil). Since it will be somewhat difficult to do something physical/hands on for quantum...

Does the \langle \phi \rangle means \langle0|\phi|0\rangle? What does |\phi| exactly mean?

Hi all. My first post. I hope I posted in the right section. I watched ep 1 of these old videos lecture by Richard Feynman and wondering if it's still valid. Or should I take on his ideas and formula my own understand from all possible views. Or how should I learn this subject. http://...

Homework Statement An electron is confined in a box where a = 60nm, b = 20nm, c = 35nm. For each of the first four quantum levels above the ground state give: a) The quantum numbers b) The speed of an electron trapped at that level c) The wavelength of light needed to excite an electron...

would anyone say that quantum physics is at all connected to spirituality? i know that there are physicists out there that would [i've read books by them] but what's the general opinions...or what's your opinion?

My knowledge on this subject is near to nothing, but I would be very much interested in learning some of the basics. Could anyone provide me with some online resources that could help me gain some understanding of this field of physics. Thanks.

I've been reading a bit about electrons and quarks, and each has been, at one time or another, described as having a certain amount of 'spin'; when I think of spin, I imagine a spherical object rotating around some central axis--this can't be correct, can it? Can an electron really... move in...

Hey, I've been thinking about getting into quantum physics, and I just wanted to ask whether it's very difficult or not. What does the mathematics involve? Is it something that someone other than an experienced mathematician can handle? Maybe I should check out relativity first...

hey everyone, could any of you recommend a good introductory quantum physics book? the thing is...i'm just interested in physics in terms of curiosity. I'm not doing physics major or anything. i always keep hearing how relativity and quantum theory are the two most believed...

I'm in Quantum right now and I'm having lots of trouble with some homework...Any help would be appreciated. If you guys could show how it's done, it would be very helpful. 1. If the Earth (of radius R = 6370 km) absorbed all photons incident on it from the Sun, what magnitude of force would...

"The conception of objective reality of the elementary particles has thus evaporated not into the cloud of some obscure new reality concept but into the transparent clarity of a mathematics that represents no longer the behaviour of particles but rather our knowledge of this behaviour.''...

Video: Conan O'Brien vs Jim Carrey: Quantum Physics http://www.milkandcookies.com/link/58968/detail/

I find quantum theory fascinating, because it fundamentally changed the perception of science. Before quantum theory everything was definate, things had a definate position, things interact in a definitve way, but quantum theory does away with all of that by saying that the most accurate model...

The density of states can be expressed in terms of Green's functions and is defined as the imaginary part of the Green function (multiplied by 1/Pi). Can someone explain me what happens if the imaginary part is just 0? It would be the case if all Eigenvalues of the Schrödinger equation are...

I can't find a definite answer, and I need to know for a statement. Am I correct saying that Quantum Physics, is the physics behind particles at a microscopic scale? And that all the Physics I learned on my course, modelling particles for real life situations (momentum, mass on a plane...

Help me please... Can anyone suggest me the books and websites that gives me the basic idea of quantum physics? I will be very greatful to him.

Hi everyone, I am not much of a quantum physicist but love reading texts on QP. I have a small problem and maybe, I thought, users of this forum can help me out. About 10 years ago, when I was still a teenager, I remember reading a book on Quantum Physics. I still remember the book was a...

hi I have this question about time in quantum physics: how does quantum physics consider time? Is it absolute or relative? Or otherwise, when one makes calculations in quantum physics do they use same time or relativity-based time?

Hi everybody , I am trying self-studying these days and I am looking for the answers of questions in the book of mathematics of classical and quantum physics (authors are Frederick W.Byron and Robert W.Fuller).If anyone has answers , could he/she notice me ? Suggestions about how to solve...

Homework Statement Solve for u(r) in the region r>R (i.e r goes towards infinity). Show that psi(r)=(A/r)e^-alpha*r Homework Equations \frac{\(d^2u(r)}{dr^2}=\alpha^2u(r) \(u(r)=\psi(r)*r The Attempt at a Solution...

I am a student in Australia,NSW I am looking for Bachelors & Degrees in University. Quantum Physics looks very interesting, but i don't know what life careers i want to use it for and I don't know any jobs that acquires Quantum Physics within it. Like can anyone tell me what pathways are there...

hi! is quantum physics that difficult to understand? because i had read the explanations given in the internet but couldn't get any proper explanation. thankz in advance! (ps. please explain quantum in simple)

Heads up . . . I have not formally studied quantum physics, but I do read about it and watch videos by some of the greats. I understand the conflict between the "micro" and "macro" physics, but I do no understand most of the details of quantum physics. Now, Tom Green enters the picture. He...

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How can quantum physics applied in our daily life?

Hi, can i know two phenomena related to quantum physics ?? hi all can i knw two phenomena related to quantum physics ??

I am very new to quantum physics.Now i would like to know how a photon moves. Is it in a straight line,or is it in a wave like pattern?

I am looking for a book containing a concise treatment of Quantum Physics at the level of Resnick and Brehm. I find these two books to be a bit wordy. Any suggestions are much appreciated. Thank you very much for your help.