- #1
genius2687
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I'm looking at a question to a practice exam. It states the following.
Imagine the universe is a spherical cavity at a temperature of 3K. Using this assumption, estimate the total number of photons in the universe.
Notes: integral[0->infinity,{x^2dx/(e^x-1)*dx}=2.4
black body energy density:
u = h_/(pi^2*c^3)*w^3/(e^((h_w/(kT))-1)
I need to find out the number of photons per unit volume (N/V). Once I have that, I can find what I'm looking for.
Any ideas on how to solve this?
Imagine the universe is a spherical cavity at a temperature of 3K. Using this assumption, estimate the total number of photons in the universe.
Notes: integral[0->infinity,{x^2dx/(e^x-1)*dx}=2.4
black body energy density:
u = h_/(pi^2*c^3)*w^3/(e^((h_w/(kT))-1)
I need to find out the number of photons per unit volume (N/V). Once I have that, I can find what I'm looking for.
Any ideas on how to solve this?