Radar cross section – Radar – Radio frequency – Radio transmitter – Radio – Railroad – Railway electrification system – Rankine cycle – Rapid transit – Reactive power – Real-time operating system – Receiver (radio) – Rechargeable battery – Reciprocity (electromagnetism) – Record player – Rectifier – Rectiformer – Recursive least squares – Reed switch – Regenerative braking – Regenerative circuit – Reis telephone – Relaxation oscillator – Relay – Reliability engineering – Reluctance motor – Remanence – Remote racking system – Remote Sensing – Renewable electricity – Renewable Energy Certificates – Renewable energy payments – Renewable energy policy – Repeating coil – Repowering – Repulsion motor – Resettable fuse – Residual current circuit breaker – Resistive circuit – Resistivity – Resistor – Resistors – Resolver (electrical) – Resonant cavity – Resonant inductive coupling – Reverse engineering – RF connector – RF engineering – RG-6 – Rheoscope – Rheostat – Right hand grip rule – Ripple (electrical) – RLC circuit – Robotics – Robust control – Rogowski coil – Root locus – Root mean square – Rotary converter – Rotary encoder – Rotary switch – Rotary transformer – Rotary variable differential transformer – Rotation (mathematics) – Rotor (electric) – Routh–Hurwitz stability criterion – Routh–Hurwitz theorem –