batteryThe cell or cells that supply a circuit's energy. Inside are two different metals and a solution called an electrolyte. Electrons leave from the end marked negative.
closed circuitA circuit with no gap in it, so current keeps going. Turning a light on closes its circuit: electricity flows along one wire, through the bulb and back along the other.
conductorA substance that passes current on with little loss. In a metal the moving charges are electrons. Each one only has to nudge its neighbor along for the current to flow.
currentMoving charge, counted by how much passes each second. It is measured in amperes, amps for short. An ampere means that one coulomb of charge passes each second.
electric circuitLinked parts that give current a route home again. Electricity flows only when the path is complete. In a circuit diagram the wires are treated as ideal, with no resistance of their own.
insulatorA substance used to keep current where it belongs. Its electrons are tightly bound to their atoms and cannot readily move. Most insulators are non-metals, and no insulator is perfect.
Show all 36 terms (30 more)
Circuit basics, continued
open circuitA circuit with a break in it, which stops the current. Turning a light off opens its circuit. The voltage between the two unconnected ends is called the open-circuit voltage.
parallel circuitA circuit that forks, so current has a choice of ways. The current can take different routes, so it differs from branch to branch. The voltage across each branch is the same.
resistanceHow hard a part makes it for charge to pass. It is measured in ohms. Each lamp added to a series circuit raises the resistance of the whole circuit.
series circuitA circuit whose parts follow one another on one route. There is only one way around, so the current is the same in every part of it.
switchA part that makes or breaks the path on purpose. The usual kind has metal contacts. Current passes while they touch and stops when they are apart.
voltageElectrical pressure, the reason charge moves at all. Its unit is the volt. Power lines carry high voltage over long distances, and transformers lower it for homes.
Circuit parts 12
circuit symbolA small standard drawing that stands for one part. The symbols for wires, batteries, resistors and other parts are largely the same from country to country.
electrodeA conductor that links a circuit to a nonmetal part. A battery has two of them, one for each metal. The word was made in 1833 from Greek words for amber and for a path.
electrolyteA substance that carries current as moving ions. In a battery the electrolyte is the solution that the two metals sit in. Solid electrolytes exist as well.
heating elementA part made to get hot when current runs through it. The coiled wire inside an electric toaster is one. The heating of a wire by the current in it is called Joule heating.
integrated circuitMany tiny parts built together on one silicon chip. It is also called a microchip. Jack Kilby made the first one, out of germanium.
junctionA meeting point of wires, where the current divides. The current flowing into a junction equals the current flowing out of it. The rule is known as Kirchhoff's current law.
power supplyA device that gives a circuit the voltage it needs. It converts current from a source into the voltage, current and frequency that a device needs. A desktop computer has one built in.
printed circuit boardA flat board whose copper tracks join the parts. The tracks are etched from sheets of copper. The board itself does not conduct, and the most common kind is made of glass epoxy.
push buttonA switch worked by the press of a finger. Buttons are usually made of plastic or metal, with a surface shaped to fit a finger.
resistorA component that adds a set amount of resistance. Resistors are also used to divide voltages. The power a resistor takes from the circuit leaves it as heat.
semiconductorA material, such as silicon, that conducts only partly. Germanium is another. Adding impurities to the crystal, called doping, changes how well it conducts.
solar cellA slice of silicon that gives a voltage in sunlight. A single silicon cell gives about half a volt, so cells are joined together to make solar panels.
Measuring 12
conventional currentCurrent pictured as positive charge on the move. In a metal wire the charge is carried by electrons, which are negative, so they move the opposite way.
electrical energyThe energy delivered as charge moves through a circuit. Power companies sell it by the kilowatt-hour. An electricity meter keeps a running total of what each customer has used.
kilowatt-hourThe unit of energy that electricity is billed in. A 40-watt light bulb left on for five hours uses 0.2 of a kilowatt-hour. One kilowatt-hour equals 3.6 megajoules.
Ohm's lawV = IR: voltage is current multiplied by resistance. Georg Ohm described it in a work published in 1827. Materials that do not obey it are called non-ohmic.
ohmmeterA meter that measures resistance. It sends its own current through the part, measures the voltage and works out the resistance by Ohm's law. A multimeter can do the same job.
overloadA draw of more current than the wires can safely take. Too great a load on a circuit is one cause. Fuses and circuit breakers protect the wiring from the damage it would do.
potential differenceThe textbook name for voltage between two points. It is the energy that each unit of charge hands over between one point and the other.
short circuitAn accidental shortcut that sends a surge of current. It can overheat wires and start a fire. It often happens when the insulation on a wire breaks down.
superconductorA material that loses all resistance when cold enough. Superconductivity was discovered in mercury in 1911 by Heike Kamerlingh Onnes. A current in a loop of superconducting wire can keep flowing with no power source.
total resistanceThe combined resistance of all the parts of a circuit. In series it is the sum of the separate resistances. In parallel it is always less than the smallest of them.
variable resistorA resistor with a knob or slider to change its value. A volume control and a lamp dimmer are variable resistors. Another name for one is rheostat.
voltage dropThe voltage lost across one part or wire of a circuit. In a series circuit the drops across the parts add up to the voltage of the supply. A drop in the supply wires is energy lost as heat.
How this list was compiled: Term list chosen for this site on 2026-10-15. Each meaning is written in our own words and was checked that day against the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: the articles Electrical network (a circuit as a closed loop with a return path), Node (circuits), Electric current, Ampere, Voltage, Electrical resistance and conductance, Electrical conductor, Insulator (electricity), Switch, Series and parallel circuits (one path, branches, the voltage drops that add up, total resistance in series and in parallel), Open-circuit voltage, Electric battery, Resistor, Push-button, Heating element, Electrode, Electrolyte, Electronic symbol, Kirchhoff's circuit laws (junctions), Integrated circuit, Printed circuit board, Power supply, Semiconductor, Solar cell, Short circuit, Ohm's law, Voltage drop, Electrical energy, Kilowatt-hour, Superconductivity, Potentiometer (variable resistors and the rheostat), Overcurrent, Ohmmeter and Volt. Open circuit, closed circuit, potential difference and overload rest on their entries in Wiktionary, the free dictionary (https://en.wiktionary.org/). Checked a second time against the Electricity explained pages of the U.S. Energy Information Administration (https://www.eia.gov/energyexplained/electricity/): Batteries, circuits, and transformers (the two metals and the electrolyte of a battery, the conductor, the load, the complete path, the switch that opens and closes a circuit, voltage as electrical pressure and transformers) and Measuring electricity (watts, kilowatts, the kilowatt-hour and the 40-watt light bulb); and against BBC Bitesize (https://www.bbc.co.uk/bitesize/), Series circuits and Parallel circuits: one loop and one route, separate branches, the same current everywhere in series, added lamps raising the resistance, the same potential difference across every branch, potential difference as energy transferred by each unit of charge, and what happens to the other lamps when one fails. The fact after each meaning is from the same pages. Licence: own work
How it works
This electric circuits vocabulary worksheet asks for twelve matches: electric circuit, current, voltage, resistance, conductor, insulator, switch, series circuit, parallel circuit and three more terms, each to be joined to its meaning. The key comes out as a second page.
Read the full guide
Parts of a circuit and how they are drawn
Set opens on Circuit basics. Circuit parts has resistor, push button, heating element, electrode, electrolyte, circuit symbol, junction, integrated circuit, printed circuit board, power supply, semiconductor and solar cell.
Measuring a circuit
The third set has short circuit, Ohm's law, potential difference, voltage drop, total resistance, conventional current, electrical energy, kilowatt-hour, superconductor, variable resistor, overload and ohmmeter.
Wire, bulb, fuse, ammeter and voltmeter are words on the electricity word search, not terms here.
Questions and answers
What are the parts of an electric circuit?
A source of power, such as a battery; a conductor, usually wire, to carry the current; a load, such as a light bulb, that uses the electricity; and often a switch that opens and closes the path.
What happens if one bulb goes out in a series circuit?
They all go out. A series circuit has only one path, so a failed bulb leaves a break that stops the current everywhere. In a parallel circuit the other lamps stay lit, because the current still has their branches to flow through.
What is the difference between a watt and a kilowatt-hour?
A watt measures power: how fast electricity is being used at one moment. A kilowatt is 1,000 watts. A kilowatt-hour measures energy, the amount used over time: one kilowatt kept up for one hour.
Who invented the battery?
The Italian physicist Alessandro Volta. His voltaic pile was the first battery, and the volt, the unit of voltage, is named after him.