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1. A gas that absorbs light of wavelength 500 nm in the laboratory. Suppose there is a c

Homework Statement a gas that absorbs light of wavelength 200 nm in the laboratory. Suppose there is a cold cloud of the same gas between you and a hot source of continuum (blackbody) radiation, and the cloud is moving away from Earth. You will see a spectrum with Homework Equations...
2. Need help on this differential equation

Homework Statement Well this is a physics problem, need find the potential function Homework Equations \Psi =Axe-kx A and k are constants I need to find d2 \Psi/dx2 The Attempt at a Solution I thought u would just take the derivative two times but just d\Psi/dx = Ae-kx-kAxe-kx...
3. How to find distance of star using inverse square law

Homework Statement So i need to calculate the distance of some star the luminosity is 2 Lo and on earth its seen as .1 Lo Homework Equations I=L/4piR2 F=L/4piR2 The Attempt at a Solution I found two formulas, but not sure what to use. The F is flux density, and I am not sure how I...
4. How to show that the universe is static( not expanding)

Homework Statement how can i show the universe is static and not expanding, how it really is. Homework Equations \OmegaM=... \Omega\Lambda=... The Attempt at a Solution "The expansion history of the universe depends on the amount of matter (gravity), quantified by \OmegaM...
5. I got a question about dark energy

Hey I have a project about dark energy. Part of it is that I need to make some kind of homework problem with this topic. The article talked about using 1a supernova data to see the expansion of the universe. I was I would first calculate the luminosity or whatever they did. Than using that...