Armature

Armature, pronounced AHR muh chuhr, is the coil of wire in which electric current is produced in an electric generator. The rotating coil in an electric motor also is called an armature. See Electric generator; Electric motor.

In a direct current generator, the armature is wound on an iron core. Electricity is produced in the coil when it is rotated in a magnetic field created by stationary electromagnets. In most alternating current generators, the armature coil remains stationary. Electricity is produced as a result of the changing magnetic field created by a set of rotating electromagnets.

In an electric motor, a current is passed through the armature coil, making it an electromagnet. The attraction and repulsion (pushing away) between the magnetized armature and stationary electromagnets in the motor cause the armature to rotate.

Contributor: Douglas M. Lapp, Ed.D., Director, National Science Resources Center, National Academy of Sciences/Smithsonian Institution.

Armature

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