Nuclear induction is the detection of nuclear spin magnetization through the voltage it induces in a receiver coil. In nuclear magnetic resonance, magnetization precessing transverse to the applied field creates a time-varying magnetic flux and hence an alternating electrical signal.
After excitation, this signal can decay as a free induction decay, whose Fourier transform gives a frequency-domain spectrum. The detection is collective: the coil measures an ensemble magnetization rather than tracking one nucleus. The phrase also recalls early experiments establishing inductive observation of nuclear magnetic resonance.
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