Subject: What energy and field is needed for an atom magnetic dipole transition?

I was wondering what energy is needed for a magnetic dipole transition (We can 
do this in pratice?)? Also what would make it change; type of force and 
magnitude? I was also wondering with energy of a atom when the proton and 
electron spins are aligned is higher than when they are not aligned. So the 
transition between these two states can occur through emission of a photon 
through a magnetic dipole transition. So when they are not aligned and the 
photon has been emitted does the spin orientation remain as is? Or will it 
want to go back to the previous state?

Re: What energy and field is needed for an atom magnetic dipole transition?