Hydrogen excited with polarized light?

[atomqwerty]

Hello,
First of all, i know I should use the template for this, and I apologize for that, but the thing is I don't even know how to begin to solve the next problem, and it's very important for me and for my tomorrow's afternoon exam. It's quite qualitative, and I'm sure most of you will know the answer very quickly. Here it goes:

Hydrogen in its fundamental state is excited with lineal polarized light, and the return to lower states is observed. When the hydrogen is put in a magnetic field with Z direction, there are not new frequencies in the spectrum. However, the emission is unfolded in two lines when the direction of polarization is turned Pi/2. Justify this fact and say what is the direction of polarization in those two cases.

Thank you so much, I really appreciate your help.

 

[anjelin]

The direction of polarization is accepted to take the direction of electric field vector of light.
In first case, when there is not an external magnetic field the direction of polarization is in the direction of electric field vector of linear polarized light. If light is propagating in z direction then electric vector is perpendicular to the z direction, e.i. it lies in (x,y) plane. If there is not new frequencies in spectrum when hydrogen is put in the magnetic field then probably the light propagates perpendicular to the external magnetic field. The electric vector of light is parallel to the magnetic field, e.i. the direction of polarization is in the z direction.When the direction of polarization is tuned pi/2, then the electric vector is perpendicular to the magnetic field, e.i. the direction of polarization is perpendicular to the z direction.

 

[atomqwerty]

Thank you, that was helpful ;)