Recent content by Orbital

Is it correct that the intensity is related to the amplitude as I \propto A^2 and the incoming amplitude is related to the scattered amplitude as A' = A \cos \theta so that the scattered intensity is I_s = A^2 \cos^2 \theta and the degree of polarization becomes \Pi = \frac{I - I_s}{I + I_s}...

Homework Statement A beam of unpolarized radiation is incident upon an electron. Show that the degree of polarization in the light scattered at an angle \theta to the incident beam is \Pi where \Pi = \frac{1- \cos^2\theta}{1+ \cos^2 \theta}. 2. The attempt at a solution This is a...

Uhm, has it got something to do with 3d space?

They are essentially the same?

Maybe the particles have the speed of light? But what about the energy in the problem statement?

I'm not sure... I found a formula \tau_{coll} = \frac{1}{n \sigma_{wk} c} where n = 0.2 \left( \frac{k_BT}{\bar{h} c} \right)^3 is the number density. This would give \tau_{coll} \propto \frac{1}{T^5} but this is not it, is it?

The number density and the speed of the particles i guess.

I cannot find any such formula...

Homework Statement Cross-sections for weak interactions at an energy E increase with E as E^2. Show that the rate of weak interactions in the early universe depends on the temperature T as \sigma_{wk} \propto T^52. The attempt at a solution The only formula I can find is \sigma_{wk} = g_{wk}^2...

Can you tell me why the phrasing of the problem is physically incorrect?

Homework Statement Estimate the mass of water vapor that is contained in 1 m^3 of saturated air at a temperature of plus 20 degrees Celsius 2. The attempt at a solution I looked up the saturation pressure for water vapor at the given temperature. Can I just use the ideal gas-law for the...