Understanding De Broglie Matter Waves: How to Simplify E/p=c^2/v?

AStaunton
Messages
100
Reaction score
1
Just a very quick question:

in my notes I have the velocity of a DeBroglie wave is given by:

\nu\lambda=2\pi\nu\frac{\lambda}{2\pi}=\frac{\omega}{k}=\frac{E}{p}=\frac{c^{2}}{v}

I can't figure out how he want from E/p=c^2/v.

I think the assumption is made that E is approximately equal to mc^2+(1/2)mv^2 and p=mv:

\implies\frac{E}{p}=\frac{m_{0}c^{2}+\frac{1}{2}m_{0}v^{2}}{m_{0}v}

but I still can't see how the above simplifies to c^2/v!
 
Physics news on Phys.org
Try using the relativistic formulas for E and p, rather than the low-speed approximations.
 
Thread 'Need help understanding this figure on energy levels'
This figure is from "Introduction to Quantum Mechanics" by Griffiths (3rd edition). It is available to download. It is from page 142. I am hoping the usual people on this site will give me a hand understanding what is going on in the figure. After the equation (4.50) it says "It is customary to introduce the principal quantum number, ##n##, which simply orders the allowed energies, starting with 1 for the ground state. (see the figure)" I still don't understand the figure :( Here is...
Thread 'Understanding how to "tack on" the time wiggle factor'
The last problem I posted on QM made it into advanced homework help, that is why I am putting it here. I am sorry for any hassle imposed on the moderators by myself. Part (a) is quite easy. We get $$\sigma_1 = 2\lambda, \mathbf{v}_1 = \begin{pmatrix} 0 \\ 0 \\ 1 \end{pmatrix} \sigma_2 = \lambda, \mathbf{v}_2 = \begin{pmatrix} 1/\sqrt{2} \\ 1/\sqrt{2} \\ 0 \end{pmatrix} \sigma_3 = -\lambda, \mathbf{v}_3 = \begin{pmatrix} 1/\sqrt{2} \\ -1/\sqrt{2} \\ 0 \end{pmatrix} $$ There are two ways...
Back
Top