RESISTANCE.--The opposition offered by a wire or other conductor to the passage of a current.
RESISTANCE, AERIAL.--The resistance of the aerial wire to oscillating currents. This is greater than its ordinary ohmic resistance due to the skin effect. See Resistance, High Frequency.
RESISTANCE BOX.--See Resistor.
RESISTANCE COUPLING.--See Coupling, Resistance.
RESISTANCE, HIGH FREQUENCY.--When a high frequency current oscillates on a wire two things take place that are different than when a direct or alternating current flows through it, and these are (1) the current inside of the wire lags behind that of the current on the surface, and (2) the amplitude of the current is largest on the surface and grows smaller as the center of the wire is reached. This uneven distribution of the current is known as the skin effect and it amounts to the same thing as reducing the size of the wire, hence the resistance is increased.
RESISTIVITY.--The resistance of a given length of wire of uniform cross section. The reciprocal of conductivity.
RESISTOR.--A fixed or variable resistance unit or a group of such units. Variable resistors are also called resistance boxes and more often rheostats.
RESONANCE.--(1) Simple resonance of sound is its increase set up by one body by the sympathetic vibration of a second body. (2) By extension the increase in the amplitude of electric oscillations when the circuit in which they surge has a natural period that is the same, or nearly the same, as the period of the first oscillation circuit.
RHEOSTAT.--A variable resistance unit. See Resistor.
RHEOSTAT, CARBON.--A carbon rod, or carbon plates or blocks, when used as variable resistances.