Question

Were introduced to concepts involving matter and electromagnetic energy, including light.why are elements like Neon used in neon signs? Another place you can see line spectra at work is in street lamps. Most street lamps today are either sodium or mercury vapor lamps (mercury lamps are slowly being phased out). By looking at the light coming from the lamp how could you tell the two apart?

We also looked at the quantum properties of the electron, but it is important to note that these quantum properties also apply to neutrons and protons. We use one of these properties, spin of the proton, in a common medical diagnostic system. Do a little research and tell me what this piece of medical technology is called.

Answer 1

NMR and MRI are the magnetic diagnostics using these properties.

Nuclear Magnetic Resonance is an important tool in chemical analysis. As the name implies, it uses the spin magnetic moments of nuclei (particularly hydrogen) and resonant excitation. Magnetic Resonance Imaging uses the same principle to get an image (of the inside of the body for example).

In basic NMR, a strong static B field is applied. A spin of proton in a hydrogen nucleus then has two energy eigenstates. After some time, most of the protons fall into the lower of the two states. We now use an electromagnetic wave (RF pulse) to excite some of the protons back into the higher energy state. Surprisingly, we can calculate this process already. The proton's magnetic moment interacts with the oscillating B field of the EM wave.