R

RMS value: Rms value of an AC sine wave is 0.707 times the peak value.

radar Acronym for "radio detection and ranging"

reactance Its Symbol is "X". Opposition to current flow without the dissipation of energy.

receiver Unit or piece of device used to receive information.

rectification Process that converts alternating current to direct current.

rectifier Diode circuit that converts alternating current into pulsating direct current.

regulated power supply Power supply that maintains a regulated and constant output voltage under changing load conditions.

regulator Device or circuit that maintains and regulates a desired output under changing conditions.

relay Electromechanical device that opens or closes contacts when a current is passed through a coil. E.g Photo Timer

reluctance Resistance to the flow of magnetic lines of force.

resistance Symbolized "R" and measured in ohms. Obstruction in path of current.

resistor Component composed of material that opposes flow of current.

resistor color code Coding system of colored stripes on a resistor to indicate the resistor's value and tolerance value.

resonance Circuit condition that occurs at the frequency where inductive reactance (X_L) equals capacitive reactance (X_C).

reverse bias Bias on a PN junction that allows only leakage current (minority carriers) to flow.

reverse breakdown voltage Amount of reverse bias that will cause a PN junction to break down and conduct in the reverse direction.

reverse current Current through a diode when it is reverse biased.

RF Abbreviation for "radio frequency."

rheostat Two terminal variable resistor used to manage current.

ripple frequency Frequency of the ripple present in the output of a DC source.

ripple voltage The small changess in Dc voltage that are left out after filtering in a power supply.

rise time Time for the leading edge of a pulse to rise from 10% of its peak value to 90% of its peak value.

rms Abbreviation for "root mean square"