# De-Broglie waves

1. Aug 10, 2008

### zimo

1. The problem statement, all variables and given/known data
A proton is accelerated from rest through a potential of 1kV. Find its de Broglie wavelength.

2. Relevant equations
$$\lambda=h/p$$

3. The attempt at a solution
I tried to get p (momentum) by energy comparison:

e*1000=0.5*m*v^2
v=437 621.130 016 524 m/s

which doesn't makes sense... what am I doing wrong?

2. Aug 10, 2008

### nicksauce

Do you mean 437621.130016524 m/s? Or 437,621,130,016,524 m/s? If the first, then that is roughly what I get when using google calculator (but why so many places after the decimal??), why doesn't it make sense to you? If the second, then that indeed doesn't make sense ,and I would recommend trying to put in the numbers again.

3. Aug 10, 2008

### zimo

Oh snap!
It didn't make sense since I used planck constant with eV*s units all the time instead of J*s units... :grumpy:

Thanks nicksauce.