Aerospace Glossary Letters R


REA – Abbreviation for Rural Electrification Administration. A branch of the U.S. Department of Agriculture responsible for the standardization of the independent telephone companies throughout the U.S. 
Reactance – The opposition offered to the flow of alternating current by inductance or capacitance of a component or circuit.
Recovered Diameter – Diameter of shrinkable products after heating has caused it to return to its extruded diameter.
Reference Junction – The junction of a thermocouple which is at a known reference temperature. Also known as the "cold" junction, it is usually located at the emf measuring device.
Refractive Index – Ratio of light velocity in a vacuum to its velocity in the transmitting medium.
Repeater – A transmitter and receiver combination used to regenerate a signal.
Resin –A synthetic organic material formed by the union (polymerization) of one or more monomers with one or more acids.
Resistance – A measure of the difficulty in moving electrical current through a medium when voltage is applied. It is measured in ohms.
Retractile Cable – A cable that returns by its own stored energy from an extended condition to its original contracted form.
RFI – Abbreviation for Radio Frequency Interference.
RG/U – Abbreviation for Radio Government, Universal. RG is the military designation for coaxial cable in Mil-C-17 and U stands for general utility.
Ribbon Cable – A flat cable of individually insulated conductors lying parallel and held together by means of adhesive film laminate.
Ridge Marker – One or more ridges running laterally along the outer surface of an insulated wire for purposes of identification.
Root Mean Square (RMS) – The effective value of an alternating current or voltage.
Rope Lay Conductor – A conductor composed of a central core surrounded by one or more layers of helically laid groups of wire.
Rupture – In the breaking strength or tensile strength tests, the point at which the material physically comes apart, as opposed to elongation yield strength, etc.