Final answer:
Net magnetization refers to the alignment of low thermal energy protons with an external static magnetic field, an effect described by the equation U = −μ · B, which determines the potential energy of protons in the field. This is a key concept in understanding phenomena in NMR, MRI, and cosmic radiation effects like the Van Allen radiation belts. Proton alignment increases the net magnetization, which can be affected by external influences like thermal collisions.
Step-by-step explanation:
The accumulated amount of low thermal energy protons that align with the external static magnetic field is known as net magnetization. In a magnetic field, the potential energy (U) of a proton is related to its magnetic moment (μ) and the external field (B) in which it is located. This potential energy can be described by the equation U = −μ · B. When a proton's magnetic moment is parallel to the field, the potential energy is minimized, and the proton is in a more stable state.
Through various energy transitions that are quantized, protons can align or realign with the magnetic field. These transitions can lead to the emission of radiation or absorption of energy, thereby conserving the total energy of the system. It is the interaction of these many proton magnetic moments aligning with the field that constitutes the net magnetization observable in systems such as those used in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).
In high-energy contexts, such as in cosmic rays or the Van Allen radiation belts, protons can be trapped by a planet's magnetic field, indicating the powerful influence that such fields have on charged particles. Within such fields, only a small fraction of protons will be aligned at any given moment due to the interference of thermal collisions with the alignment process.