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HarleyM
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Homework Statement
Compare and contrast a 2.2 eV photonn with a 2.2 eV electron in terms of energy(J), rest mass (Kg) speed (m/s) wavelength (m) and momentum kgm/s.
Homework Equations
For Photon
P=E/C
F=E/h
V=fλ
λ= h/P
For Electron
λ=h/mv
m=E/C2
p=h/λ
Ke=1/2mv2
The Attempt at a Solution
Photon
2.2 ev X 1.6x10-19= 3.52 x10 -19 J
P=E/C
P= 3.52 x10 -19 / 3 x 108
P= 1.17 x10 -27
f= E/h
=3.52 x10 -19 /6.63x10-34
F=5.31x1014
v=fλ
v= 3x108 m/s
λ= h/P
=6.63X10-34/1.17X10-27
=5.66X10-7 m
m=? ( Does a photon have a rest mass?) I don't think a photon has a rest mass.
Electron
2.2 eV x1.6x10-19 = 3.52 x 10-19 J
Should rest mass be the standard 9.11 x10-31 kg
Or should I calculate using E=mc2
m= E/C2
m= 3.52 x 10-19 / (3x108)2
m=3.91 x10 -36 kg
( I use 9.11 x10-31 kg as the mass for the rest of the calculations but I can change it if its incorrect and the calculated mass should be used! )
Ek=1/2mv2
3.52 x 10-19=1/2 (9.11x10-31)v2
v= √[(3.52 x 10-19)(2)/9.11x10-31]
v=8.79x105 m/s ( Unsure whether I can use this equation to determine speed)
λ=h/mv
= 6.63x10-34/(9.11X10-31)(8.79X105)
=8.28X10-10 m
p= h/λ
=6.63x10-34/8.28X10-10
=8x10-25 kgm/s
Parts I have highlighted is where I am unsure! Thanks for all the help!
If I have misused any equations ( i.e used matter equations for light or vice versa can you please alert me! )