Barrier Definition and 241 Threads

Homework Statement Ok, maybe I'm slow at grasping this, but why is the potential energy U of an electron while it is tunneling through a 1 dimensional potential barrier of height V0 = V0? Homework Equations Schrodinger equation in 1D (using semiclassical approximation) The Attempt...

I am doing a computational project in my undergraduate Quantum Physics course on tunneling through a potential barrier. But, it's an irregular potential barrier, so I cannot simply use the results from a textbook. The first diagram, with corresponding wave equations, are shown in the first...

Homework Statement find the wavefunction of a particle in a potential V(x)= 0, |x|< a V, |x|< b (V>0) (Infinity), |x|>=b ground state energy 0<=E<=V Homework Equations The Attempt at a Solution i know the wavefunction has to be equal to zero at...

Can you gurus help me understand in a qualitative way the nature of the Coulomb barrier as it applies to alpha decay? I can intuitively appreciate the Coulomb barrier as it applies to an incoming charged particle, but resources I have been reading apply the same term to the barrier felt by...

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Hi, It is stated that changing the medium - water to ethanol f.ex - the experimentally measured rate enhancement is 10^6 fold which leads to a lowering of the activation barrier of \approx 9 kcal/mol. I don't quite understand which parameters I am missing in order to calculate that? Any help...

I am dealing with the classic problem of a potential barrier of finite width, with a particle tunneling through, in the case of E < V. I am to calculate the transmission/reflection coefficients, and we first start off with the wavefunctions for the three regions. Before the barrier, we...

I got a question about an infinite potential barrier. If a particle with a momentum p travell through an infinite potential barrier, how can the energy be conserved, thus how can the particle have the same momentum after passing the barrier? Does there exists any real life example?

If you have a Potential Barrier V (width a) and particles incident on left with energy E where E>V, are the following true: Classical Physics: - All particles will be transmitted past the barrier - It cannot be reflected because that would mean it has negative E which is not possible...

If you have a Potential Barrier V (width a) and particles incident on left with energy E where E>V, are the following true: Classical Physics: - All particles will be transmitted past the barrier - It cannot be reflected because that would mean it has negative E which is not possible...

Hi there, I am a grade 11 student, learning physics. Homework Statement A driver of a car going 90km/h suddenly sees the lights of a barrier 40.0 m ahead. It takes the driver 0.75s before he applies the brakes and the average accelleration during braking is -10.0m/s2. a) Determine...

The Coulomb potential barrier of a system of two nuclei X and Y is approximately given by VC = ZX*ZY*e2/RN where ZX and ZY are the charge numbers of the nuclei, e2 = 1.44 MeV*fm, RN = (AX1/3+AY1/3) × r0 is the sum of the nuclear radii. r0 is a constant usually estimated to 1.2 to 1.3 fm and AX...

Off course we should not take too seriously what we read in Sci Fi books. I've just been to lazy to do any research into the concept of a galactic barrier which was introduced to me in a trilogy of books called the 'Q Continium' by Greg Cox. So if anyone knows if such a barrier does exist then...

I have a couple questions about finite potential barriers that I can't seem to figure out on my own... 1) Why does the real part of the wave function collapse inside the barrier (square, rectangular, barrier with V less than the energy of particle)? It seems to me that there should be some...

Ok, so I've been dealing with this problem for a while and can't figure it out. (I tried to clean it up, but I don't know LaTeX, hopefully it is more clean in post #2; problem stated in #1, and my work in #2) --Consider a (plane-wave) particle tunneling through a rectangular barrier...

Question: What happens when the energy of the state is exactly equal to the barrier it hits? Say the particle is traveling to the right and hits the barrier. Before hitting, you have your typical solutions, say Aexp(ikx) + Bexp(-ikx). After hitting, the V(psi) and E(psi) terms cancel...

a concept came up that that there is a one to one barrier with motors and generators. Is there such a thing? the only i am aware of would be relative to Newtons law (egual and oppisite reaction) if you put a number in is that the only number you have out? or can it be increase ( i thought that...

Since these seem to be popular around here these days, I thought I'd another to the mix :) "A particle of mass m and energy E > 0 approaches a potential drop -V0 from the left. What is the probability that it will be reflected back if E = V0/3? The potential energy is V(x) = 0 for x<0 and...

My question is about West Nile Virus and why/how it is much more likely to cause encephalitis in the elderly. What I've found is that increased permeability of the BBB is what allows the virus to infect brain tissue which is how the majority of neurological damage is done. The rest of the...

Given a delta function barrier located at x=0: V(x) = +a * delta(x) If you have a particle incident from the left with E<0, what does the wave function look like?? I have trouble with this because I thought the particle energy needed to be greater than the minimum potential (E > Vmin) for...

After having spent some time trying to learn differential geometry and differential topology (my background is in physics phenomelogy) I can`t help making the following observation. I think it is harder to learn the maths starting from a background in physics than learning the math from...

gravity barrier?? Hello all...first post I have a question about a "gravity barrier" that exists. I was in a discussion about the space shuttle launch that took place a few weeks ago and somehow we got on the subject of a gravitational barrier. Meaning the shuttle had to break at 4000 mph...

Hi, just got into the topic of relativity and got curious. Is it possible to break the light barrier similiarly to the sound barrier? I have just found an article that someone had done it. http://www.lastek.com.au/light.htm What are your views on this?

How do you break the barrier from getting good grades to truly pursuing mathematics/science as a lifelong thing? i do what i like to call "good enough to get an A" but i want to step it up and reach that next level, where it's more research oriented. any thoughts?

We have a particle of energy E crossing a potential jump at x=0. for x<=0, V=0, for x>=0 V=V1 We get a wavefunction for x>=0 psi(x) = exp(-iEt/hbar)*exp(-Kx) where K = (2m(V1-E))^0.5/hbar N.b E<V1 so classically we get no transmission we are asked to estimate the penetration distance, and...

Hi there, Was wondering about the potential barrier problem when Eo>V. I have figured out the expression for the Transmission coeffient (after a lot of algebra) and am now wondering, what happens when I vary the width of the barrier, obviously there is greater transmission when the barrier...

This pic is really cool, it looksl ike a cloud. I'm only 17, so don't know much physics, i hope someone can explain this in an easier way. Why does it look like a cloud

i don't quite understand how it operates. from what i read it seems the image force is part of the barrier. but the textbook says it reduces the barrier. which is which?

I can't work out what I am doing wrong in this question. Anyways, here it is: A 3.0 MeV proton is incident on a potential energy barrier of thickness 10fm and height 10 MeV. What is the transmission coefficient T. And here is what I have tried: T=e^(-2bL) b=\sqrt{\frac{8\pi^2m(U_b-E)}{h^2}}...

I have a quesion regarding a quantum physics assignemnt, I wonder what units I should use when calculating the transmission coefficient of a quantum barrier problem. I have got the following expression: T = \frac{4(E+V_0)}{(2E+V_0)cos^2a\sqrt{\frac{2m}{\hbar^2}(E-V_0)} +...

When an object breaks the sound barrier, sounds "lag" behind that object as it travels faster, theoretically the same can be said for light. Would this work the same for time? If you exceeded whatever limit this barrier has would time "lag" behind you?

I am developing a rubbery serpentine wall as a highway median barrier and I need to know the tensile strength necessary to hold against a 4400 lb pickup moving 62.5 mph. Using an excel spreadsheet and iterations, I subtract the momentum of the wall from that of the pickup at 2 foot intervals...

I have some questions about barrier tunneling in a scanning tunneling microscope. From what I know, the microscope consists of a one atom tip very close to the surface of the metal being examined. A potential difference is applied between the tip and the metal and some of the electrons manage...

This is my second post after that of "Shuttle Main Engines" in which I use again the question: what is happening here? First of all, open the .jpg file below. It shows a F-4 Phantom breaking the sound of barrier. I'm interested on what happens in the condensated flow. First of all, why is...

In quantum mechanics particles which do not classically have enough energy to pass through a barrier do so. But surely there is no mystery here if the energy of the barrier is not as great as it is thought to be. Charged particles from space could be penetrating the barrier and cancelling...

I have a question to do but I am a bit confused about one thing. It invloves protons penetrating a barrier. The protons ae quoted to have a KE in the units of eV (which i will have to convert to joules in order to work in SI units). However the barriers height is given in volts. I assumed...

Friend asked me this question ,and I wasn't about answer. Not my area of expertise). I guess rocket gets easier trough the sound barrier than millitary jet aircraft due to somewhat "less" problematic geometric shape. I mean there is no such problems with wings and drag like in aircrafts?

If a bullet exits a barrel at 3000fps. Does the breaking of the sound barrier by the bullet influence the BOOM that you hear. Thank you.

Its something that I should be able to figure out easily but my brain is refusing to work this term. So any help will be appreciated. In a scattering experiment, gold nuclei (Au Z=79 A=197) are bombarded by alpha particles (He Z=2 A=4) If the Kinetic Energy of the apha particles is...

A new claim has appeared in physics. It is claimed that there is a largest possible force, namely c^4/4G or 3 x 10^43 Newton. (The claim is made in the paper http://xxx.lanl.gov/abs/physics/0309118 ) All my friends and acquantances have first said "wrong!" but then failed to produce a...

[SOLVED] Underwater barrier [?] Since I've been lookin a the concept and knowledge to what happens when the sound barrier gets broken and how it happens, it got me thinking about if the same thing can happen in water. i.e. If an object was to move faster than the water molecues could move what...