# Potential diffrenece required to accelerate electron from rest to acquire certain wavelength

1. Oct 6, 2014

### gxc9800

1. The problem statement, all variables and given/known data
Calculate the potential difference required to accelerate electron from rest to acquire wavelength of 0.154nm

2. Relevant equations

3. The attempt at a solution
eV = hc / λ
(1.6x10^-9) (V) = (6.63x10^-34)(3x10^8)/ 0.154x10^-9
V = 8072V ....
here's the sample ans :

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2. Oct 6, 2014

### nasu

It's about an electron. There is no speed of light in the formula for momentum of the electron.
You are mixing up things.

I think there is a typo in the book. The denominator in the last formula should be $\lambda$ and not mv.

3. Oct 6, 2014

### BiGyElLoWhAt

It is a typo, but they still used lambda where you would expect them to plug in (incorrectly) v.