Energies Definition and 299 Threads

Homework Statement Tasks to do: a.)give voltage b.)give the absolute value of charge density for plates Presumably the absolute values of charge densities for plates is equal between the two of them. An electron is accelerated in a homogenic electric field, inbetween two oppositely charged...

If a quantum sistem can vibrate only in discreate energies, can there exist photons of all energies (All frequencies in the real number line)?

Homework Statement I'm currently working on a homework set for my intermediate QM class and for some reason I keep drawing a blank as to what to do on the first problem. I'm given three potentials, V(x), the first is of the form {A+Bexp(-Cx^2)}, the others I'll leave out. I'm asked to draw the...

Then is potential energy infinite (potential energy=energy that can be created)

Is the velocity of two photos of same radiation(light) with different energies same ?? (also in Same medium) Will energy alter the velocity of photon?

Homework Statement [/B] A nail is heated in a bunsen burner flame and is about to be dropped into a beaker of water at room temperature. a) Which of the two substances (nail or water) would you expect to initially have: i) the highest internal energy ii) the highest average kinetic...

Homework Statement Kindly refer to part (c). The woking should be power/0.35 (what I think according to the graph). But the answer is power (that is the answer of part b) divided by 0.02 Homework Equations I have used the ratio method simply The Attempt at a Solution According to part (b)...

Hello everyone, How come the electron wave energy states are different for spin -½ and +½ values? What causes this asymmetry?

Homework Statement The longest homerun hit by Miguel Cabrera in the 2012 season occurred at Comerica Park and had an initial y-component of velocity of 19.8 m/s and an initial x-component of velocity given as m/s, where is some value left undetermined. Assume the ball left the bat 1.22 m off...

Homework Statement Assume a particle with a wave function ##\psi(x)## such that ##-\infty < x < \infty##, that move under some potential ##V(x)##. Show that: a) two wave functions with same energies can only differ by a complex phase; b) if the potential is real, then you can choose the wave...

I understand that the photon energies given by the Planck-Einstein relation, though highly precise, are approximations. But have they been confirmed at all experimentally or in practice? If so, across the board or just some of them?

Homework Statement Here is the problem: http://imgur.com/XEqE4SY Homework Equations |psi_s_ms> = |s, ms> ⊗ Σ D_i_j |psi_i, psi_j>[/B]The Attempt at a Solution I know the singlet state in the |s, ms> basis is |0,0> = (1/sqrt(2))[ |up, down> - |down, up>] and that the hamiltonian for this...

Hi,I'm new here, and created my account solely for following question: Does the incompatibility between QM and Relativity indicate a phase transition at high energies? (as in: indicate more than a "could be")

Donor ionization energies are calculated via the hydrogen-like model and use the static dielectric constant and effective mass to modify the screening between the electron and the donor. Nice and simple, I get it. But in a material the ionized electron needs to go someplace - presumably the...

How to compare the ground state energies if diagrams containing x vs V are given. I saw a problem containing diagrams three potentials and they have asked to arrange them in order of their ground state energies. One was a potential well, and the other two had small perturbation in the middle...

Homework Statement Given that the bond energy of hydrogen-hydrogen bonds is 436 KJ/mol, that of hydrogen-oxygen bonds is 464 KJ/mol, and those in oxygen molecules 496 KJ/mol, what is the approximate heat of reaction for 2H2 + O2→2H2O Homework Equations Hproducts-Hreactants The Attempt at a...

Homework Statement Why is it harder to rip off a paired electron than an unpaired electron? I'm trying to work out why the ionisation energy is lower for chlorine than for argon. Homework Equations Configuration for argon: $$1s^22s^22p^63s^23p^6 $$ Configuration for chlorine...

Homework Statement Homework EquationsThe Attempt at a Solution 6C-H bonds= 410 x 6 = 2460 kJ/mol 3C-C bonds H of formation= +53.3 kJ/mol H of atomisation = +717 kJ/mol H-H = 436 kJ/mol as H of formation is 53.3, can't I just do: 2460+3x=53.3? But then I am not using a lot of the values...

Hi, I am wondering about additional solutions to the particle in a box problem. In the one dimension the wave functions allowed all make sense with nodes pinned to an infinite potential barrier at either end and then divided into node increments related to the length of the box. However, in 2...

Homework Statement Calculate the average potential and kinetic energies for the electron in the ground state of hydrogen. Homework EquationsThe Attempt at a Solution I know that KE = E - <U(r)>. I know that E = (-KZ^2e^2)/(2a0) and I know that U(r) = -KZe^2/r but I can't figure out how to...

Hello, today our teacher told us that on tomorrow's test there is going to be a problem where you drop a mass on a slope which connects into a loop. The point of the problem is to calculate exactly how tall the slope must be for the mass to complete exactly one course through the loop...

Hi, The Hamiltonian for the free scalar field, expressed in terms of the creation/annihilation operators, is H = \int d^{3}p [\omega_p a^{\dagger}_p a_p + \frac{1}{2}\omega_p \delta^{3}(0)] \hspace{3mm} I thought: \omega_p is a function of p as \omega^{2}_p = |p|^{2} + m^2 and so the...

In the canonical formulation of QFT (to which I've been exposed), it is always argued that only differences in energy are physically observable and so we can deal with the fact that the vacuum energy is infinite by redefining the vacuum such that its energy is zero and we subsequently measure...

Recently I've been in a discussion with someone online who claimed that the efficiency of a computer with regards to energy is not a linear relationship. I assumed that if you were to halve the power going into a computer chip (assuming it was designed to deal with that and wouldn't just turn...

Hello, I consider an ideal superconductor with the gibbs-energy $$ d G=-SdT + VdP - \mu_0 M V dH$$ and helmholtz energy $$ dF = -SdT -P dV + \mu_0 V H dM$$ Assuming, that in the normal state the magnetization is too small, so that G_n(H) = G_n(H=0) and at the transition point H_c the...

I have one question which I need to verify as a thought. Suppose I have a particle collider for symmetric energies e^\pm, that give as a result the Y(4S) resonance which later decays in B mesons. Then the lab-frame is equivalent to the rest frame of the e^\pm system and the Y(4S) is at rest in...

Hi! I would like to ask some general question about IR spectroscopy. During absorption of IR photons two quantities have to be conserved, energy ##\hbar \omega_{photon} = \hbar \omega_{phonon}## and momentum ##\hbar k_{photon} = \hbar k_{phonon}##. Wouldn't these two quantities be conserved at...

Title should be: Are photon energies constant along null geodesics? [Mentor's note: Title corrected] As I understand it in general relativity the paths of light rays, given by null geodesics, are scale invariant. Is that correct? Now Maxwell's equations in flat Minkowski spacetime are also...

On the Ultra-high-energy cosmic rays Wikipedia page there is an explanation that the 'effective' energy of cosmic rays differs from the actual(?) energy; and that 'only a small fraction is available for interaction'. How can that be, why isn't all energy 'effective'? "The energy of this...

Homework Statement Positronium is a hydrogen-like atom consisting of a proton and an electron revolving around each other. Find the allowed radii and energies of the system. Homework Equations See solution attempt. The Attempt at a Solution The allowed radii of the positron/electron system...

Hi Why kinetic energy of photoelectrons rise up to a maximum? Thanks

Starting from the FRW metric (for simplicity flat space, radial direction only): $$ds^2=-c^2dt^2+a(t)^2dr^2$$ If we take dt=0 then the proper distance ds(t) between two spatially separated points at cosmological time t is given by: $$ds(t)=a(t)dr$$ Now at the present time t_0 we can define...

Homework Statement Just one more nuclear question if I may, Homework Equations None. The Attempt at a Solution I can do the first part of this question, but am unsure on the second part. I thought it may be related to the Q-factor (the difference in energy of the initial and final products...

Hello, I was wondering if someone could explain to me what does it meant that a beta particle has a range of energies ? Thanks

Hi there, new to this website so please bare with me if I break any rules and let me know for future. I am a maths and physics tutor but occasionally I come across a question I just cannot work the answer for. In this case I know the answer but I can't get to it. 1. Homework Statement...

Homework Statement Neglecting hydrogen-bonding, calculate the interaction energy between (i) H3O+ and H2O and (ii) H3O+ and H3O+, if each pair is separated by 0.3 nm and assuming that the aqueous solvent can be treated as a medium with constant relative permittivity. Using your result...

Homework Statement Why does ## \frac{ e^+ + e^- \rightarrow \mu^+ + \mu^- }{e^+ + e^- \rightarrow \tau^+ + \tau^- } \rightarrow 1## at high energies? Would it be the same if it was ## \frac{ e^+ + e^- \rightarrow \mu^+ + \mu^- }{e^+ + e^- \rightarrow e^+ + e^- }##? Homework EquationsThe...

Homework Statement Estimate the energies of interaction at 25 °C between (i) two hydrogen molecules and (ii) two nitrogen molecules, if each pair is separated by 0.3 nm. Explain fully and clearly your reasoning and any assumptions you make in your answer. State the source of the values of any...

Hello! Well this is a quite embarrassing problem but I think my maths has disappeared the last years. So I"m working on some calculations and i want to compare with the expermental data but there's a shift on energy that it has to be apply. So I thought I just need to to a simple calibration...

The reaction p→n+e++νe is common inside nucleus. But it not considered when we talk about free particle and reason is simply given mass of products being larger than reactants. Now my question is if there is a high energy proton having total energy in order of 2 GeV or let it to be 100 GeV (To...

Hello ! How does the inclusion of a fraction of the HF "exact exchange energies" in an hybrid functional (B3LYP for example) can degrade the quality of the results ? I mean that the results are worst than expected because of the HF exchange, but if we call it "exact" how is it possible ? Thank...

Why are such high beam energies required at particle colliders to produce new physics/particles? The Higgs particle has energy of ~MeV so why are ~TeV energies required? Furthermore, by what mechanism does the energy get converted into particles/mass?

I was reading a section of a chemistry textbook describing electron energy shells. It compares the electrons to light saying that electrons energies are quantized and so are light energies. Electrons can only jump from one specific energy level to another with no intermediary energy levels. I...

Hi, so I'm a first year neuroscience student at Carelton University in Canada. I had a little bit of a "revelation" with this topic recently after I understood it a bit better and I think this is really interesting. (If I understand it correctly!) We're learning about Kekule structures...

Hey all, This is a problem I can't really wrap my head around. 1.) The lanthanoid series is formed through the progressive filling of the 4f subshell, whereas the first row transition metal series is formed through the progressive filling of the 3d subshell. a) What is the relative...

Hi there I am trying to find bound state energies assuming infinite potential. I have been told it can be done by analytically solving Right Hand Side and Left Hand Side of an equation such as: E^1/2 tan(2ma^2E/4hbar)^1/2 = (V0-E)^1/2 If solved properly, it should give one curve (RHS), crossed...

Homework Statement A horizontal spring with psring constant k = 15.19 N/m is compressed 23.11 cm fro mits equil. position. A hockey puck with mass m = 170.0g is placed against the end of the spring. The friction coefficient is 0.02221. How far does the hockey puck travel? k = 15.19 N/m x =...

Greetings, I was wondering if anybody knew whether or not the moment of wavefunction measurement is always associated with a high energy. I know that we require smaller and smaller wavelengths of light to probe smaller distances, and since energy increases as wavelength decreases, I was...

Homework Statement Two objects of inertias m1 and m2 start from rest and then interact with each other (assume neither is interacting with any other object). What is the ratio of their kinetic energies at any instant? Homework Equations \frac{K_{1}}{K_{2}} = ? The first part of the equation...

Hi All, I just have a question regarding potential energies. Say I have a block above a spring, and I define the potential energy of gravity and the spring to be zero at the uncompressed point. I then drop the block, trying to find the maximum compression of the spring using conservation of...