A measuring instrument in which current or voltage is determined by the force of attraction on a bar of soft iron pivoted within the magnetic field of a fixed coil or by the repulsion between the poles induced in two soft iron rods within the coil. As the deflection caused by the passage of a current through the coil does not depend on the direction of the current, moving-iron instruments can be used with either d.c. or a.c. without a rectifier. They are, however, less sensitive than moving-coil instruments.
A measuring instrument that depends for its operation on the interaction between current-carrying fixed coils and soft-iron pieces in the moving system. The attraction-type of instrument depends on the attraction of the coil for a soft-iron armature when the magnetic flux due to the current in the coil changes (Fig. a). The repulsion-type of instrument depends on the mutual repulsion between two soft-iron rods located inside the coil (Fig. b). Since both are contained within the coil similar poles are induced in adjacent ends.
Moving-iron instruments
- volcanic bomb
- volcanic centres
- volcanic conduit
- volcanic cone
- Volcanic Constructs
- volcanic dome
- volcanic dust
- volcanic-exhalative processes
- Volcanic Explosivity Index
- volcanic haze
- volcanicity
- volcaniclastic
- volcanic neck
- volcanic pile
- Volcanic Plains
- volcanic plug
- Volcanic units
- volcanism
- volcano
- volcano-tectonic depression
- vole
- Volgian
- volition
- volonté générale, volonté de tous
- Volstead Act (1919)