Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
Britannica Sources used in this answer

How does magnetic resonance occur in a strong magnetic field?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Figure 1: Precession of a magnetic dipole moment Ī¼ in the presence of a constant field H and a rotating field Hā€² (see text)
magnetic resonance Figure 1: Precession of a magnetic dipole moment Ī¼ in the presence of a constant field H and a rotating field Hā€² (see text)

In physics, magnetic resonance occurs when particles with magnetic momentsā€”such as atomic nuclei or electronsā€”are placed in a strong, constant magnetic field.21

When these particles are subjected to this field, they act like tiny gyroscopes, causing their spin axes to precess around the direction of the magnetic field at a specific rate known as the Larmor precession frequency. Because of quantum mechanics, these particles can only occupy specific, discrete magnetic energy states.21

To induce resonance, a weak, oscillating magnetic field is applied perpendicularly to the strong constant field. When the frequency of this oscillating field matches the Larmor frequency of the precessing particles, the system enters a state of resonance. During this process, the particles absorb or emit energy as they transition between their discrete magnetic energy states. This energy exchange is then measured by a spectrometer to analyze the properties of the matter being studied.21