The constant field and the pulse field are usually set perpendicular to each other. This maximizes the NMR signal strength. The resulting response by the total magnetization (M) of the nuclear spins is the phenomenon that is used in NMR spectroscopy and magnetic resonance imaging. Both use intense applied magnetic fields (H) in order to achieve dispersion and very high stability to deliver spectral resolution. Scientist explain their readings as chemical shifts, the Zeeman effect, and Knight shifts (in metals).