- #1
Dansuer
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Homework Statement
Consider a particle on a ring with radius R in a plane.
The Hamiltonian is [itex]H_0 = -\frac{\hbar^2}{2mR^2}\frac{d^2}{d\phi^2}[/itex]
The wavefunction at t=0 is [itex]\psi=ASin\phi[/itex]
Find the mean value of the observable [itex]Sin\phi[/itex]
Homework Equations
The eigenfunction are
[itex]\psi_n = \frac{1}{\sqrt{2\pi}e^{in\theta}}[/itex]
with eigenvalues
[itex]E_n = \frac{n^2\hbar^2}{2mr^2}[/itex]
The Attempt at a Solution
First i find the state of the system
[itex]\psi=ASin\phi =A \frac{e^{i\phi}-e^{-i\phi}}{2}=\frac{\left|1 \right\rangle -\left|-1\right\rangle}{\sqrt{2}}[/itex]
Then i have to calculate
[itex]\left\langle \psi \left| Sin\phi \right| \psi \right\rangle[/itex]
but i don't know how to deal with a function of the operator. I though about expanding it in a taylor series but it does not seem to work.
Any help it's appreciated