# Homework Help: De Broglie Wavelength of an electron

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1. Oct 15, 2014

### Janet

1. The velocity of the electron in the ground state of the hydrogen atom is 2.6 x 10^8 m/s. What is the wavelength of this electron in meters?

2. De Broglie's equation: lamda = h/p
p=mv

3. The attempt at a solution...

(6.626 x 10^-34) / (2.6 x 10^8 x 9.11 x 10^-31)

= 2.798 x 10^-12 meters

This isn't the right answer...obviously...

2. Oct 15, 2014

### e.bar.goum

Quickly (sorry, posting and running), and with wolfram alpha, I get 1.7 * 10^-12 m. Which doesn't sound too far off to me (and neither does your answer), considering 2.6 * 10^8 m/s is about 500 keV of kinetic energy for an electron.

Why do you suspect your answer wrong?

3. Oct 15, 2014

### Simon Bridge

Is the electron relativistic enough to make a difference?
Is the wavelength consistent with DeBroglie's hypothesis about the allowed energies of the electron?

4. Oct 16, 2014

### ehild

Check the problem text. The speed of the electron is much less than the speed of light in the ground state of the H atom.

ehild