1. A chopper (a device that interrupts an electric current or a beam of radiation) in which an electromagnet driven by a source of alternating current sets into vibration a reed carrying a moving contact that alternately touches two fixed contacts in a signal circuit, that periodically interrupts the electrical signal.
2. A fundamental property of matter in which it exhibits two states, positive and negative, that result in the action of electric forces in the presence of an electric field.
3. A chopper apparatus that uses an electromagnet driven by an AC source to vibrate a reed which periodically interrupts an electrical contact.

A chopper is a device for interrupting an electric current, a beam of light, or a beam of infrared radiation at regular intervals, to permit amplification of the associated electrical quantity or signal by an alternating-current amplifier. It is also used to interrupt a continuous stream of neutrons to measure velocity.