# Lamor precession and diamagnetism

1. Nov 4, 2011

### Gavroy

i have some troubles to understand the lamor precession properly and i need your help to correct my errors:

so in order to get the lamor precession: afaik you need something that causes a magnetic moment, e.g. an electron with spin or angular momentum.

then you need a homogenous magnetic field and it is necessary, that the direction of the field and the direction of the magnetic moment are not exactly the same if you want to measure at least something.

now, there is a torque, that leads to this movement with constant angular velocity
is this right so far?

but: at this point i heard, that it has something to do with diamagnetism and this is what actually confuses me.

diamagnetism means, that the body creates a magnetic field that is opposed to the external magnetic field.

but if this torque that is caused by the lamor precession leads to an additional magnetic field, how do you know, that it is always opposed to the external one?

and which equation gives me the internal magnetic field, that is caused by the lamor precession?

sorry for my english, i am still practising.

2. Nov 5, 2011

### Naty1

English: is good, I understand your questions just fine.

You mean Larmor precession.

Try reading here: do you understand vector equations?

http://en.wikipedia.org/wiki/Larmor_precession

Also note the APPLICATIONS links near the end of the article.

just as you know friction always opposes an applied force....so electrons will try to return to their original orientation which is in opposition to the applied external magnetic field.

http://en.wikipedia.org/wiki/Diamagnetism

3. Oct 29, 2013

### anorred

Diamagnetic resonance

Can the electrons/protons of a diamagnetic material be resonated? I understand that you cannot detect a signal from diamagnetic materials because the signals from each electron cancel each other out. However, can the electrons/protons be excited at certain frequencies just like hydrogen (one proton) in MRI?