# Help! Quantum Mechanics

1. Sep 12, 2007

### Ming0407

my Q1 ans. when U=100v, wavelength=1.228 x 10^-10 m
when U=10000v, wavelength=1.228 x 10^-11 m

Q2 ans. help me........

Last edited: Sep 12, 2007
2. Sep 12, 2007

### Kurdt

Staff Emeritus
Welcome to PF! I'm afraid you will need to show your attempt at a solution before anybody can help you. It is the policy of this forum.

3. Sep 12, 2007

### Ming0407

Sorry, i don't know the policy of this forum. Anybody can help me?

4. Sep 13, 2007

### Kurdt

Staff Emeritus
Question 1 seems to be fine. You've found the momentum and used the de Broglie wavelength equation. For question 2 you will have to use the plane wave $\Psi (x,t) = Ae^{i(kx-\omega t)}$ in the wave equation and perform the differentiations. Then you should be able to do part one and part two.

5. Sep 13, 2007

### Ming0407

i don't know how to perform the differentiation. because i have not study differentiation, i don't know question 2 too.

6. Sep 13, 2007

### malawi_glenn

Well why are you doing QM if you haven't done enough math before?

And there are tons of tutorials on the internet on calculus. Do you want us to show you some of those?

7. Sep 14, 2007

### TimNguyen

You're taking QM and have not taken Calculus I?

How is that possible?

8. Sep 14, 2007

### Kurdt

Staff Emeritus
I'm not sure we can help you other than giving you the answer in that case, which is against the spirit of the forum. I could spend 30 minutes typing out a tutorial on how to differentiate exponentials but frankly I don't think it would help when you have never taken any calculus and you're doing a QM course.

I must ask, are you self-studying or on a college or university course?