De Broglie Wavelength for 1Mev electron

[Phynos]

Homework Statement

Calculate the de Broglie Wavelength of a 1 MeV electron. Express your answer in femptometers.

Homework Equations

$λ = h/p$
$p = (2mT + T^2/c^2)^{1/2}$

The Attempt at a Solution

basically just plugged everything in.

$λ = \frac{h}{(2mT + T^2/c^2)^{1/2}}$

$λ = \frac{(4.126*10^{-15}eV*s)}{(2*(0.511*10^6 eV)(10^6 eV) + (10^6 eV)^2/c^2)^{1/2}}$

$λ = 4.09*10^{-21}$

Which is way too low. It's supposed to be $872*10^{-15}$.

 

[TSny]

Watch the units. You entered a mass in units of energy (eV).