# Search results

1. ### Fourier Properties (shifting)

Hi, I need help with some basic fourier transform properties stuff - its fairly simple though I think I am doing something wrong. So we know from the shifting property if h(x) has the fourier transform H(f) then h(x-a) has the fourier transform H(f)ei*2*π*f*a so I have the function cos(2πf0x...
2. ### Wave function at infinity

Okay thank you. I think it is sufficient for my course. I appreciate your time!
3. ### Wave function at infinity

I think I see what you are saying. I will give a little more information into what I am trying to do. The question is: Consider two normalizable wave functions Ψ1(x, t) and Ψ2(x, t), both of which are solutions of the time-dependent Schrodinger equation. Assume that the potential function is...
4. ### Wave function at infinity

We aren't given any. Some other information which might be helpful though, the wave function is normalized, it is a solution to the time dependent schrodinger equation and the potential function is real. And again it approaches zero as x goes to +- infinity. Is that enough?
5. ### Wave function at infinity

Homework Statement If I have a wave function that goes to infinity can I assume that the derivative also goes to 0 at infinity? Homework Equations The Attempt at a Solution The reason I think it does is because the wavefunction and its derivative must be continuous everywhere...
6. ### Average energy mass on a spring

ah okay thanks!
7. ### Average energy mass on a spring

Homework Statement Hi, I hope this isn't a silly question. I am looking to find the mean potential energy of a mass on a spring with spring constant k and maximum displacement x0. Homework Equations The Attempt at a Solution I know the maximum energy is 1/2*kx0^2 so would the...
8. ### Quantum well combination

I did some work on c, hopefully someone can give me a reply to this to make sure I am on the right path. so I said that the solution is similar to the finite potential well. In region A which is between -b and -a the wavefunction is of the form: \psi = Aexp(kx) + Bexp(-kx) (I know that...
9. ### Quantum well combination

Can anyone help please? If I am being unclear please let me know
10. ### Quantum well combination

Homework Statement The question is attached as a picture. Note: if someone would prefer I type it out I can. Homework Equations Schrodingers equation The Attempt at a Solution PART A I am pretty sure I got the well right. It looks like a finite well inside an infinite well. I...
11. ### Stirlings approx/CoinFlips/Gamma function

Please ignore number two, it required that the terms left off to be added. Still need help with 1 and 3
12. ### Stirlings approx/CoinFlips/Gamma function

Homework Statement Hi I actually have three questions that I am posting here, help in all of them would be greatly appreciated! 1) Prove that ln(n!) ≈ nln(n)-n+ln(2*pi*n)/2 for large n 2)Supposed you flip 1000 coins, what is the probability of getting exactly 500 heads 3) Show that n! =...
13. ### Estimate energy of infinite well (ground state)

Homework Statement We have to estimate the ground state energy of an infinite potential well (1d) using an argument based on the heisenberg uncertainty principal. We then are supposed to compare it with the exact value from the eigenvalue equation. Homework Equations Below The...
14. ### Planck Black-Body Law

Homework Statement Starting from the Planck-Body Law I_{λ}dλ = \frac{2\pi c^{2}h}{λ^{5}} \frac{1}{e^{hc/(λkT)} - 1}dλ where λ is the wavelength, c is the speed of light in a vaccuum, T is the temperature, k is Boltzmann’s constant, and h is Planck’s constant, prove that the total energy...
15. ### Free Current

I mostly understand that. The answer the book gives for I free is = (I*pi*s^2)/(pi*R^2) which makes sense, but I am looking for what definition they used exactly to get that. What equation?
16. ### Free Current

Homework Statement I am looking at an example problem in the text and they skipped some steps. I think I am missing somthing obvious but none-the-less I don't know what is going on. We have a long copper rod o radius R which carries a uniformly distributed (free) current I. Find H, the...
17. ### Determining Wave Equation

Homework Statement One end of a long horizontal string is attached to a wall, and the other end is passed over a pulley and attached to a mass M. The total mass of the string is M/100. A Gaussian wave pulse takes 0.12 s to travel from one end of the string to the other. Write down the...
18. ### Energy of a system

Hi guys, so I figured out my main problem with this question. I am having troubles coming to terms with the fact that were using a cylinder but the charge is given in terms of the linear charge density. So when using gauss's law, what is the charge enclosed? Is it just lamba * l?
19. ### Energy of a system

sorry I wiorked a little bit, is the electric field E = λ/(2*ε0) * (s^2-a^2) where s is the radius on between a and b? Edit: I did some looking around and worked a little more and here is where I am at. The electric field in between the two cylinders is \frac{λ}{2*pi*ε0 * s} where s is...
20. ### Energy of a system

Homework Statement There are 2 long coaxial insulating cylinder. The inner and outer cylinders have radii of a and b and charge densities λ and -λ uniformly distributed on the surface. Calulcate energy per unit length 2 ways (equations below) Homework Equations W = \frac{1}{2}\int σ...
21. ### Simple Harmonic Motion

Right whoops. so then v = dx/dt i + dy/dt j and when we cross them we get m(xdy/dt - ydx/dt) = L correct?
22. ### Simple Harmonic Motion

Homework Statement Two-dimensional SHM: A particle undergoes simple harmonic motion in both the x and y directions simultaneously. Its x and y coordinates are given by x = asin(ωt) y = bcos(ωt) Show that the quantity x\dot{y}-y\dot{x} is also constant along the ellipse, where here the...
23. ### Divergence physics homework

Okay thank you again!
24. ### Divergence physics homework

So =\frac{[V_{y}(x,y,z)-V_{y}(x, y-\frac{1}{2}Δy,z)]}{\frac{1}{2}Δy} =V_{y}(x,y,z) - V_{y}(x,y,z) + \frac{∂v_{y}}{∂y}(\frac{1}{2}Δy) / (\frac{1}{2}Δy) =\frac{∂v_{y}}{∂y} correct? Sorry for the poor formatting I am still getting used to this latex stuff
25. ### Divergence physics homework

Hey guys, I would really appreciate some help so if there is something I was unclear about let me know and I will try and clarify further thanks.
26. ### Divergence physics homework

Homework Statement In deriving the formula div v = \frac{∂v_{x}}{∂x} + \frac{∂v_{y}}{∂y} + \frac{∂v_{z}}{∂z} we used a rectangular solid infinitesimal volume; however, any shape will do (although the calculation gets harder). To see an example, derive the same formula using the prism-shaped...
27. ### Magnetic field from vector potential function using tensor notation

Oh that was a mistake I knew that but thank you. You have been a wonderful help!
28. ### Magnetic field from vector potential function using tensor notation

hm. I can see how that works now but do you think you can explain that a little further if possible? Also that means then I have this left with the appropriate substituitons: \frac{1}{2}[3B_{0i} - B_{0l}δ_{li}] so then δ_{li}] = 1 only if l = i or 0 if l ≠ i changing indicies...
29. ### Magnetic field from vector potential function using tensor notation

Right we don't have a repeated index that would then = 0 because you are looking at different components correct?
30. ### Magnetic field from vector potential function using tensor notation

well it would equal 1 only if the indices are equal so then is it equal to 3 also? (because of the y and z components)? edit: looking only at the x component the indicies are summed to 3 so for the x component is it equal to 3?