An electric light bulb is connected to the network via a switch. The ensemble forms a circuit through which electrical current can flow. An electrical current can only exist if the charges can move through the whole of a closed circuit. The switch is the component that gives us control over the opening and closing of the circuit.
To enable current to flow, the materials used must be conductors:
- The electrical wires are made of copper.
- The switch’s contacts are made of iron.
- The base of the bulb is made of iron.
- The bulb’s filament is the part that has the highest resistance, but is nonethless a conductor. Most often, it is made of tungsten.
Remark: The movement of charges shown in the animation illustrates a direct current (DC). It should be pointed out that, in the usual household installation, the current is more likely to be alternating (AC) and the movement of charges corresponds to a back and forth movement of charges around an equilibrium position. The role of the switch nonetheless remains the same for the frequencies usually found in domestic use. (50 Hz or 60 Hz according to the country).