# What is the energy of one of the orange light photons?

1. Jan 15, 2006

### FateEternal

The Argon gas laser produces orange light of wavelength 6.3E-7 meters and of frequency 4.76E14 Hz. The laser output is 5.2 mW
a. What is the energy of one of the orange light photons?
b. What is the momentum of one of the orange light photons?
c. How many photons per second does this laser emit?
d. What is the realtionship between (c) and the frequency of the light

2. Jan 15, 2006

### fargoth

a. the energy of a photon is hf.
b.
from special relativity $$E^2=m^2c^4+p^2c^2$$
since the rest mass of a photon is zero, it becomes $$E=pc$$
so, $$p = \frac{E}{c}$$
since $$E = hf = h (\frac{c}{\lambda})$$,
$$p = (\frac{hc}{\lambda}) *(\frac{1}{c})$$
$$p = \frac{h}{\lambda}$$
c. okay, you know the energy per second the laser emmits right?
how many times the energy of a single photon is it?
d. whats the relation between f and c? (hint: you can find it on this post...)

Last edited: Jan 15, 2006
3. Jan 15, 2006

### FateEternal

a 6.6E-34(4.76E14)
=3.14E-19
b p=6.6E-34/6.3E-7
=1.05E-27
c 5.2E-4/3.14E-19
=1.66E15
d ...i cant see a relation between
1.66E15 photons per second
and 4.76E14 Hz
unless i did something wrong