Deflection coil

Deflection coil - a coil used for deflecting a beam of charged particles. The angular deflection is proportional to the flux density produced by the coil.

Deflection coils are often used in pairs in order to facilitate deflection in multiple directions. For instance, in cathode ray tubes (CRT) there are usually two pairs of coils (so four in total) to allow deflection in horizontal or vertical direction.