| W (unit) | True, Reactive, and Apparent power |
| Wagner earth | AC Bridge Circuits |
| watchdog timer | Time-delay relays |
| watt | Power in electric circuits |
| | Power dissipation |
| Wattmeter | Wattmeter design |
| Wave, electromagnetic | Principles of radio |
| Wave, sawtooth | More on spectrum analysis |
| Wave, square | Square wave signals |
| Wave, triangle | More on spectrum analysis |
| Waveform symmetry and harmonics | Harmonics in polyphase power systems |
| | More on spectrum analysis |
| | The TRIAC |
| Waveguide | Waveguides |
| Wavelength | Long and Short Transmission Lines |
| weber (unit) | Magnetic units of measurement |
| Weight, numeration system | Systems of numeration |
| Weston cell | Special-purpose batteries |
| Weston meter movement | What is a meter? |
| | Measurements of AC magnitude |
| Wetting current | Troubleshooting -- Theory and Practice |
| | Switch contact design |
| Wheatstone bridge | Bridge circuits |
| | Strain gauges |
| | Frequency and phase measurement |
| Wheatstone bridge, unbalanced | Mesh current method |
| Wien bridge | AC Bridge Circuits |
| Williams tube memory | Historical, nonmechanical memory technologies |
| winding, bifilar | Creating custom calibration resistances |
| winding, primary | Mutual inductance and basic operation |
| winding, secondary | Mutual inductance and basic operation |
| Wiper, potentiometer | Voltage divider circuits |
| Wire | Conductors, insulators, and electron flow |
| Wire Gauge | Conductor size |
| Wire size, gage scale | Conductor and Insulator Tables |
| Wire, jumper | Component failure analysis |
| Wire, Litz | Inductor quirks |
| Wire, magnet | Electromagnetism |
| Wire, solid and stranded | Conductor size |
| wire-wound resistor | Creating custom calibration resistances |
| Wire-wrapping | Building simple resistor circuits |
| Word | Bit groupings |
| work | Power in electric circuits |
| Working voltage, capacitor | Practical considerations |
| wound rotor induction motor | Wound rotor induction motors |
| writing memory | Digital memory terms and concepts |