There are three types of materials used in electronics: electrical conductors, electrical insulators and semi-conductors.
Electronic components are divided into two groups: discrete electronic components - such as diodes, transistors, capacitors and resistors - and integrated circuits. You need to know what the common discrete components are used for, and to understand ohms and resistance values. You also need to know how to represent components using symbols when drawing circuit diagrams.
There are three types of materials used in electronic components:
Electrical conductors are materials that allow electricity to flow through them easily.
An electrical insulator Electrical insulators are materials that prevent electrical flow. In the diagram below the insulating material (plastic) surrounds the conducting material (copper wires)
Semi-conducting materials exhibit both conducting and insulating properties. The way in which the material is connected to a power supply determines whether it will conduct an electrical current or prevent it from flowing.
The most common semi-conducting material is silicon. Silicon needs to have very small amounts of other elements such as boron and phosphorous added to it in order to become a semi-conductor. This is called doping. Doped silicon is used to make components such as:
- Integrated circuits
The simplest kind of semiconductor device is a diode. In a diode the electrical current can be made to flow in one direction only (see diagram below). If the diode is reversed the flow of current is stopped. This behaviour is due to the semi-conducting property of the doped silicon.
Another semi-conducting material is germanium, but this material is used less widely than silicon.
For the image of this experiment download here