right-hand rule
Physics
noun
1A rule for finding the direction of the magnetic field produced by a current flowing through a wire: if the right hand is placed as if to grasp the wire, with the thumb pointing in the direction of the current, the fingers curl in the direction of the magnetic field; also called Ampère's rule, Ampère's law.
2(More fully Fleming's right-hand rule) a rule for finding the direction of the current induced in a wire when it moves through a magnetic field: if the first finger, second finger, and thumb of the right hand are held out perpendicular to each other, with the thumb pointing in the direction of motion of the wire (m sound) and the first finger in the direction of the field (f sound), then the second finger points in the direction of the induced current; also in extended use.
Origin
Late 19th century; earliest use found in Nature: a weekly journal of science.