Uses of functions
A galvanometer is a very sensitive meter which is used to measure tiny currents, usually 1mA or less.
An ammeter is used to measure current.
A voltmeter is used to measure voltage.
(Fixed and Variable)
A resistor restricts the flow of current, for example to limit the current passing through an LED. A resistor is used with a capacitor in a timing circuit. This type of variable resistor with 2 contacts (a rheostat) is usually used to control current..
Capacitor: (fixed & variable)
A capacitor stores electric charge. A capacitor is used with a resistor in a timing circuit. A variable capacitor is used in a radio tuner.
Switches (SPST & SPDT)
SPST = Single Pole, Single Throw.
An on-off switch allows current to flow only when it is in the closed (on) position. SPDT = Single Pole, Double Throw.
A 2-way changeover switch directs the flow of current to one of two routes according to its position. Some SPDT switches have a central off position and are described as 'on-off-on'.
Power supply (DC & AC)
Supplies electrical energy.
DC = Direct Current, always flowing in one direction. AC = Alternating Current, continually changing direction.
Battery and cell
Supplies electrical energy. A battery is more than one cell.
The larger terminal (on the left) is positive (+).The larger terminal (on the left) is positive (+).
A single cell is often called a battery, but strictly a battery is two or more cells joined together.
Connecting wires (bridging plug, banana plug and alligator)
These are the wires used to connect the different electrical components.
Electrical bulb or lamp
A transducer which converts electrical energy to light. This symbol is used for a lamp providing illumination, for example a car headlamp or torch bulb.