- #1
chef99
- 75
- 4
Homework Statement
Calculate the momentum of a 140 eV photon.
Homework Equations
p = E/c
The Attempt at a Solution
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First, convert eV to Joules
140eV (1.60 x10-19J)
= 2.24 x10-17J
Now for momentum:
p = mv
p = (E/c2)v
p = E/c
In my course, however, it says for photons E = hc/ λ
so p = E/c
is p = hc/λ/c
p = h/λ
My question is is it acceptable to use p = E/c even though this is with a photon, as the question only gives its eV value? or is there some way that I can't think of to determine the wavelength, λ, to then be able to use p = h/λ?
I have written my answer using p = E/c below.p = E/c
p = 2.24 x10-17J / 3.00 x108m/s
p = 7.47 x10-26kgm/s
The momentum of the photon is .47 x10-26kgm/s.
I would really appreciate any help on this problem.