| Machine language | Microprocessor programming |
| Magic-Eye tube | Display tubes |
| Magnet wire | Build a transformer |
| | Electromagnetism |
| Magnet, permanent | Permanent magnets |
| magnetic amplifier | Special transformers and applications |
| Magnetic field | Magnetic fields and inductance |
| | An electric pendulum |
| | Principles of radio |
| Magnetic field, rotating | Polyphase motor design |
| magnetic flux density | Susceptance and Admittance |
| magnetic quantum number | Magnetic Quantum Number |
| Magnetism | Permanent magnets |
| Magnetite | Permanent magnets |
| magnetizing current | Mutual inductance and basic operation |
| Magnetomotive force | Electromagnetism |
| | Mutual inductance and basic operation |
| Magnetostriction | Heat and Noise |
| magnitude | Measurements of AC magnitude |
| magnitude comparator | Larger 5 & 6-variable Karnaugh maps |
| Make-before-break | Contact "normal" state and make/break sequence |
| master/slave protocol | Network protocols |
| Maximum Power Transfer Theorem | Maximum Power Transfer Theorem |
| | Special transformers and applications |
| | Sensitive audio detector |
| | Sensitive voltage detector |
| maxterm | Larger 4-variable Karnaugh maps |
| maxterm product | Sigma- and Pi-Notation |
| maxwell (unit) | Magnetic units of measurement |
| Maxwell-Wien bridge | AC Bridge Circuits |
| MC6800 | Short-distance busses |
| Mega | Metric notation |
| Megger | High voltage ohmmeters |
| | 4-Wire Resistance Measurement |
| Megohmmeter | High voltage ohmmeters |
| Meissner effect | Superconductivity |
| members of set | Venn Diagram and Sets |
| memory | Digital memory terms and concepts |
| Mercury (tilt) switch | Switch contact design |
| Mercury cell | Special-purpose batteries |
| Mercury-wetted contacts | Contact "bounce" |
| Mesh Current analysis | Mesh current method |
| Meter | What is a meter? |
| Meter movement | What is a meter? |
| | Make your own multimeter |
| Meter, power factor | Practical power factor correction |
| Metric prefix | Ammeter usage |
| metric system | Metric notation |
| | Metric prefixes and unit conversions |
| | Magnetic units of measurement |
| Metrology | Kelvin (4-wire) resistance measurement |
| Mho | Conductance |
| | Active-mode operation |
| mho, unit | Susceptance and Admittance |
| Micro | Metric notation |
| Microbending | Optical data communication |
| microchannel bus | Short-distance busses |
| Microcode | Microprocessors |
| Microphonics, electron tube | Tubes versus Semiconductors |
| Microprocessor | Microprocessors |
| Microwaves | Waveguides |
| Mil | Conductor size |
| Mil, circular | Conductor size |
| Milli | Metric notation |
| Milliamp | Ohm's Law (again!) |
| Millman's Theorem | Millman's Theorem |
| | Millman's Theorem revisited |
| minimal cost | Larger 4-variable Karnaugh maps |
| minterm | Larger 4-variable Karnaugh maps |
| minterm sum | Sigma- and Pi-Notation |
| mks system | Magnetic units of measurement |
| MMF | Mutual inductance and basic operation |
| Modbus | Extended-distance networks |
| Mode, optical | Optical data communication |
| modulation | Electrical signal types |
| Modulus. vector | Polar and rectangular notation |
| molecule | Electron activity in chemical reactions |
| monochromatic light | Laser diodes |
| monostable multivibrator | Digital logic with feedback |
| | LED sequencer |
| MOS Controlled Thyristor | Field-effect-controlled thyristors |
| MOS-gated thyristor | Field-effect-controlled thyristors |
| MOSFET | CMOS gate circuitry |
| Motor | Polyphase motor design |
| Motor, electric | Electromagnetism |
| Motor, induction | Polyphase motor design |
| | Automotive alternator |
| Motor, synchronous | Polyphase motor design |
| | Automotive alternator |
| Motor/generator set | Step-up and step-down transformers |
| Movement, meter | What is a meter? |
| | Make your own multimeter |
| MSB | Decimal versus binary numeration |
| Mu, tube amplification factor | Combination tubes |
| multi-stage amplifier | Input and output coupling |
| multibus | Short-distance busses |
| Multimeter | Safe meter usage |
| | Multimeters |
| | Voltmeter usage |
| Multimode fiber | Optical data communication |
| multiple-input gates | Multiple-input gates |
| Multiplier | Voltmeter design |
| | AC Voltmeters and Ammeters |
| Multiplier circuit, diode | Voltage multipliers |
| multivibrator | Digital logic with feedback |
| | Contact "bounce" |
| | 555 Audio Oscillator |
| | Audio oscillator |
| Multivibrator, monostable | LED sequencer |
| Mutual inductance | Practical considerations |
| | Mutual inductance |
| | Mutual inductance and basic operation |
| mutual induction | What is alternating current (AC)? |
| MWG (Steel Music Wire Gauge) | Conductor size |
