Circuits: diagrams and components

In a nutshell

Circuit diagrams are used to represent circuits in a simple and understandable manner. Each component has its own symbol such that anyone can replicate the circuit.

Circuit diagrams

To illustrate electrical circuits in a manner that is easily replicable, scientists use circuit diagrams. Straight lines are used to represent wires and they can connect different components in two ways:

• Series:
  

• Parallel:
  

Circuits in series form a closed loop where current flows on a single pathway while circuits in parallel form different loops where the current branches off in different pathways. Both of these types of circuit can be combined by having components in series with each other but parallel to other components.

Components

Each component has its unique symbol such that scientists can easily recognise them. There are:

name of component	symbol	description
Cell		This component is a power source which provides electricity for the circuit.
Battery		This component is made by two or more cells connected in series to provide a larger potential difference for the circuit.
Switch		Used to turn a circuit on or off. When it is closed the circuit is fully connected so the current can flow through it, when it is open the circuit is interrupted and therefore no current will flow.
Filament lamp		This is a type of light bulb, it produces a light when current passes through it.
Ammeter		This component is used to measure current in a circuit.
Voltmeter		This is a component that measures the potential difference between two points in a circuit. It is connected in parallel.
Resistor		This component limits the flow of current in a circuit.
Variable resistor		This is a resistor with an adjustable resistance.
Thermistor		This is a component that changes its resistance depending on the temperature surrounding it.
Diode		This component allows current to flow only in one direction.
Fuse		This component is a safety device that breaks the circuit in case too much current flows.
LED		The light-emitting diode (LED) is a semiconductor that emits light when current passes through it.
LDR		The light dependent resistor (LDR) is a component that changes its resistance depending on the light hitting it.
Capacitor		This component stores energy in the form of electrical charge.