Flip angle

Flip angle refers to the angle by which the magnetization vector of a sample is rotated in a magnetic field during techniques like Magnetic Resonance Imaging (MRI) or Nuclear Magnetic Resonance (NMR). When a radiofrequency (RF) pulse is applied to a sample in a magnetic field, it causes the nuclear spins (such as those of hydrogen atoms in water) to "flip" from their alignment with the magnetic field. The flip angle is typically measured in degrees.