1. The use of a magnetic field or external horizontal-deflection and vertical-deflection coils to deflect an electron beam in a television picture tube or an oscilloscope.
2. Deflection of an electron stream by means of a magnetic field.

In a television picture tube, the magnetic fields for horizontal and vertical deflection of the electron beam are produced by sending sawtooth currents through coils in a deflection yoke which goes around the neck of the picture tube.