Paramagnetism and Magnetic Resonance: Feynman's Physics Explained

Feynman Vol II10-11

Treated with quantum mechanics, paramagnetism reveals that atomic magnetic moments can only point in a discrete set of directions relative to a field. Transitions between these energy levels can be driven by an oscillating field at a precise resonant frequency. This nuclear magnetic resonance is an exquisitely precise tool for probing molecular structure — and is the physics behind medical MRI scanners.

The big idea

Magnetic resonance lets us read the inside of molecules — and bodies.

Think about it

How could flipping the magnetic spins of atoms inside you produce a detailed image of your body?

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