Electronics glossary
Every word explained in one sentence and one everyday picture. Tap a word for more, and for the lessons that use it.
A
- AC (alternating current)
- AC is current that keeps changing direction, back and forth, many times a second.
- Analog and digital
- A digital signal is only on or off (1 or 0); an analog signal can be any value in between.
B
- Breadboard
- A breadboard is a board with holes joined in rows inside, so you can build circuits without soldering.
C
- Capacitor
- A capacitor stores a small amount of electrical charge and releases it quickly.
- Conductor and insulator
- A conductor lets electricity flow easily (like copper); an insulator stops it (like rubber or plastic).
- Current
- Current is how much electric charge flows past a point in the circuit every second.
D
- DC (direct current)
- DC is current that flows in one direction only, like from a battery.
- Diode
- A diode lets current flow in one direction only.
F
- Forward voltage
- Forward voltage is the voltage a diode or LED needs before it starts to conduct, and keeps across itself while on.
G
- Ground (GND)
- Ground is the 0 V reference point of a circuit, the point every other voltage is measured from.
I
- Inductor
- An inductor is a coil of wire that resists changes in current by storing energy in a magnetic field.
L
M
- Microcontroller
- A microcontroller is a tiny computer on one chip that reads sensors and controls things using a program you write.
- MOSFET
- A MOSFET is a transistor switched by voltage instead of current, so it can control big loads with almost no input current.
- Multimeter
- A multimeter measures voltage, current and resistance, and checks if a wire is connected.
O
- Ohm's law
- Ohm's law says voltage equals current times resistance: V = I × R.
P
- Parallel circuit
- In a parallel circuit each part has its own path, so they all get the same voltage and the current splits between them.
- Potentiometer
- A potentiometer is a resistor with a knob, used to give a variable voltage or resistance.
- Power
- Electrical power is how fast energy is used or turned into heat, light or motion: P = V × I.
- PWM (pulse-width modulation)
- PWM switches a pin on and off very fast; the share of time it's on sets the average power, to dim LEDs or slow motors.
R
- Rectifier
- A rectifier turns AC, which changes direction, into DC, which flows one way.
- Relay
- A relay is a switch flipped by an electromagnet, so a small circuit can safely switch a big one, like a 230 V lamp.
- Resistance
- Resistance is how strongly something holds back the flow of current.
- Resistor
- A resistor is a small part that limits how much current flows in a circuit.
S
- Series circuit
- In a series circuit the parts are joined one after another, so the same current flows through all of them.
- Short circuit
- A short circuit is an accidental path with almost no resistance, so a dangerously large current flows.
T
- Tolerance
- Tolerance is how far a part's real value can be from the number on it, for example ±5%.
- Transistor
- A transistor is a switch or amplifier where a small current controls a much bigger one.
V
- Voltage
- Voltage is the electrical push that makes current flow around a circuit.
- Voltage divider
- A voltage divider is two resistors in series that give a smaller voltage at the point between them.
Z
- Zener diode
- A Zener diode is a diode made to conduct backwards at an exact voltage, so it can hold a voltage steady.
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