Recent content by Hargoth

  1. H

    Does This Lagrange's Equation for a Spring Pendulum Look Correct?

    Since the mass is attached to a spring, the length l of the pendulum is not constant.
  2. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    There always has to be time-dependence in some way. In fact, the Schrödinger and Heisenberg-Pictures are just different ways of writing down the same mathematics. There is a magical operator, call it U(t), which creates the time dependent wavefunctions out of the wavefunctions at t=0. So...
  3. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    No, you have to conjugate \Psi as well. Therefore \Psi \Rightarrow \Psi^* .
  4. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    x is an operator which is used to calculate the expectation value - the expectation value may change in time, but not the way it is calculated! If the expectation value changes, it is due to the wavefunction which changes in time. In fact, this is the perspective of the so-called "Schrödinger...
  5. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    Right, but you have conjugate it all and write out the Hamiltonian to see something. And don't forget about "i" just because it's not real, it will get mad if you do to often! :wink:
  6. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    Ah, I think you were working with what I know as "Ehrenfest's Theorem". The Schrödinger Equation is this: i \hbar \frac{\partial}{\partial t} \Psi(\vec x, t) = \left( -\frac{\hbar^2}{2m} \frac{\partial^2}{\partial x^2} + V(\vec x) \right) \Psi(\vec x, t) .
  7. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    No, you just have to take the derivative wrt time of the function (\Psi x \Psi^*) and remember that \Psi solves the Schrödinger-Equation (and \Psi^* the "complex conjugate Schrödinger-Equation" ...)
  8. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    Write down the derivative and think of the Schrödinger-Equation, then. ;) There's still an i (imaginary unit) missing, I think ...
  9. H

    How Does the Schrödinger Equation Govern the Time Dependence of Wave Functions?

    Are you sure your \frac{d}{dx} in the first equation isn't \frac{d}{dt} and some i is missing?
  10. H

    Understanding the Difference Between |z>, |+z>, and |-z> in Quantum Mechanics

    Yeah, I just wanted to say that your probability of finding z in state z from the equation above would be 2^2=4 , so you have to normalize.
  11. H

    Understanding the Difference Between |z>, |+z>, and |-z> in Quantum Mechanics

    For a QM-Interpretation you have to normalize the statevector, so that \langle z | z \rangle = 1 . If \langle z_+ | z_+ \rangle = 1 and \langle z_- | z_- \rangle = 1-, this not the case here. I wouldn't say "amplitude" but "probability": |\langle -z | x \rangle|^2 is the probability...
  12. H

    Understanding the Difference Between |z>, |+z>, and |-z> in Quantum Mechanics

    Yeah, but if | z_+ \rangle, | z_- \rangle are basekets of the Hilbert space you consider, your equation would be a definition of | z \rangle
  13. H

    How Does a Particle Inside a Rolling Cylinder Affect Its Motion?

    I think that there is an error in your Lagrangian: Since you are interested in the movement of the cylinder and watch it in the "labatory system", so to say, you can't say that the velocity of the particle in y-direction is R \dot \phi \cos(\phi). \phi is fixed in the "cylinder system", so...
  14. H

    Conservation of energy (wave in a conductor)

    Yeah, thx. Well, if you get the solution (by yourself or from the classes ;) ), I'd like to hear it. :smile:
Back
Top