# Wavelength, temperature in transition

1. Oct 23, 2008

### akance

Hi!!! I really need some help
I'm really really not good at physics...so
Here it is

1) The electron energy of a hydrogen atom is given by -C/n^2 relative to zero energy at infinite separation between the electron and the proton (n is the principle quantum number, and C is a constant). For detection of the n=2 -> n=3 transition(656.3 nm in the Balmer Series), the electron is the ground state of the hydrogen atom needs to be excited first to the n=2 state. Calculate the wavelength (in nm) of the absorption line in the starlight corresponding to the n=1 -> n=2 transition.

2) According to Wien's law, the wavelength corresponding to the maximum light intensity emited from a blackbody at temperature T is given by (wavelength)(Temperature) = 2.9 mmK
Calculate the surface temperature of a star whose blackbody radiation has a peak intensity corresponding to the n=1 -> n=2 excitation of hydrogen

3) The ground state of hydrogen is split into two hyperfine levels due to the interaction between the magnetic moment of the proton and that of the electron. In 1951, Purcell discovered a spectral line at 1420 MHz due to the hyperfine transition of hydrogen in interstellar space. Hydrogen in interstellar space cannot be excited electronically by starlight. However, the cosmic background radiation, equivalent to 2.7K, can cause the hyperfine transition. Calculate the temperature of a blackbody whose peak intensity corresponds to the 1420 MHz transition

Can you please!! help me with these 3 problems...!!!! I am so confused!!

2. Oct 24, 2008

### JoAuSc

How much of these problems can you do?