I'm an Alevel Student trying to understand the concept of NMRI, I understand that when an external magnetic field is applied, the protons either line up with (parallel) or line up against (antiparallel) the external magnetic field. Sources state that protons parallel to the field have lower energy than antiparallel protons and that there are more parallel protons than antiparallel protons.
I have difficulties understanding the concept of:
- Difference in energy between anti-parallel and parallel protons. There's an answer in quora https://www.quora.com/Why-does-a-spin-up-electron-have-slightly-more-energy-than-a-spin-down-electron explaining in terms of protons that
If the spin is already aligned with the magnetic field (up), it means that no energy is required to align it with B, which means that the spin up particle has the least potential energy.
If the spin is aligned opposite to the magnetic field (down), it means that the energy required to align it is maximum, which means that spin down particles has the most potential energy.
If the parallel protons have less potential energy, doesn't that mean that it has more kinetic energy than anti-parallel protons? Why are we only so concerned about potential energy?
- The fact that there are more parallel than antiparallel protons due to lower energy of parallel protons. Why is this so? In this link https://www.reddit.com/r/askscience/comments/2axmfz/why_do_more_protons_align_themselves_parallel/, the only reason that I could somewhat grasp was based on part of one of the answers:
Always think about Boltzmann's population distribution when you are considering problems like this.
Using my Alevel knowledge (from Boltzmann distribution curve), I understand that in a system, majority of the particles will have lower/ intermediate energy compared to higher energy. Doesn't Boltzmann Distribution curve only apply to kinetic energy and not potential energy?
There are other reasons based on Zeeman Effect which I can't seem to understand due to my limit in knowledge at this moment, but will try to read on it. At this moment, I'm looking for simpler answers that an Alevel student could understand. Thank You.