- #1
hquiquero
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Homework Statement
Find the energy (in joules), rest mass (kg), speed (m/s), wavelength (m), and momentum (kgm/s) of a 2.2 eV electron.
I'm having trouble finding the speed of the electron; once I have that I can find the wavelength and momentum.
E = energy
p = momentum
h = Planck's constant (6.63 x 10-34 Js)
c = the speed of light (3.0 x 108 m/s)
λ = wavelength
Homework Equations
1 eV = 1.60 x 10-19 J
Etotal = Ek + Erest
E = hc/λ
p = h/λ
The Attempt at a Solution
Energy of electron in joules:
2.2 eV = 3.52 x 10-19 J
Rest mass of an electron:
9.11 x 10-31 kg
****(Is this a correct answer or do I need to calculate rest mass?)
Speed of electron:
I tried this equation:
Etotal = Ek + Erest
Ek = Etotal - Erest
but it doesn't work because the total energy given for the electron is less than the rest energy calculated...
I'm not sure what equation other equation I can use. Also, I don't know if relativity must be taken into account if the electron's speed is close to the speed of light?
Thank you!