By these contactors the usual series-multiple control of direct-current motors is effected.
It will be necessary to obtain the use of a direct-current ammeter for this purpose.
Then there was a telephone transmitter which made variations in a direct-current flowing through the primary of a transformer.
The engine is belted to a direct-current generator of the shunt-wound type.
The alternating-current arc is much noisier than the direct-current arc, but with very high frequencies this noise ceases.
The alternating-current arc-lamp was developed after the appearance of the direct-current open-arc and has been widely used.
The direction of rotation of a direct-current motor can be reversed by reversing either the field or the armature current.
This humming sound is quite different from the occasional hissing of a direct-current arc.
Within this angle is included a large portion of the light emitted by the light-source in the case of direct-current arcs.
It was more efficient than the preceding lamps but was handicapped by being solely a direct-current device.
direct current |
An electric current that moves in one direction with constant strength. Batteries are a source of direct current. Direct current is not used for long-distance power transmission because it is difficult to step up the voltage to a level that is efficient for energy transfer and then to step the voltage back down again for safe domestic use. Compare alternating current. See Notes at current, Tesla.