Glossary
The terms of this app, from A to Z, each with the page that explains it.
- Ammeter
An ammeter measures the current. You put it into the circuit so that the current flows through the device.
- Characteristic curve
A characteristic curve shows how the current depends on the voltage. For an ohmic resistor it is a straight line through the origin.
- Circuit
A circuit is a closed path for the electric current, from the power source through the devices and back again.
- Circuit diagram
A circuit diagram shows a circuit with circuit symbols instead of drawings of the parts.
- Conductor
A conductor lets electric current through well. All metals are conductors, for example copper, iron and aluminium.
- Current
The current says how much electric current flows in a circuit. Its symbol is and it is measured in amperes (A).
- Fuse
A fuse breaks the circuit automatically when too much current flows, for example in a short circuit. This protects against fires.
- Insulator
An insulator (also called a non-conductor) hardly lets any electric current through, for example plastic, rubber, glass, wood and porcelain.
- Ohm's law
For an ohmic resistor the voltage divided by the current is always the same: . The resistance does not change when you change the voltage.
- Parallel circuit
In a parallel circuit the parts are connected next to each other. The current has several paths, one for each part.
- Resistance
The electrical resistance says how strongly a part hinders the current. Its symbol is and it is measured in ohms (Ω).
- Series circuit
In a series circuit the parts are connected one behind the other. There is only one path for the current.
- Short circuit
In a short circuit the current flows along a path with no load at all. The cable can get very hot, so a short circuit is dangerous.
- Switch
A switch opens or closes the circuit. Closed, the current flows; open, none flows.
- Total resistance
The total resistance is the resistance the whole circuit presents to the source. In a series circuit it is the sum of the single resistances.
- Voltage
The voltage says how strongly the power source drives the current. Its symbol is and it is measured in volts (V).
- Voltmeter
A voltmeter measures the voltage. You connect it in parallel: with its two terminals at the two ends of the part you want to measure.