Letter I
INFRA-RED - Infra-red is a type of light wave. We cannot see it because it is just outside the range of light that our eyes can detect. You can feel it, though -- infra-red light warms things and is the way an electric fire heats a room. The infra-red equipment used in the projects we have designed is not that powerful, and you will not feel any heat from it.
INTEGRATED CIRCUIT - An integrated circuit (IC) is a complete, very compact circuit made up of tiny RESISTORS, CAPACITORS, DIODES and TRANSISTORS. Each IC can contain hundreds of these components, and the circuits themselves are very complicated. However, we do not need to know the exact details, just what the IC needs as inputs and what we can expect as outputs. If you look in an electronics catalogue, you will usually only be told what VOLTAGE the IC was designed for and how each pin of the IC must be connected if it is to work properly.
INTERNAL COMBUSTION ENGINE - An engine in which fuel is burned inside the engine. A car's gasoline engine or rotary engine is an example of an internal combustion engine. It differs from engines having an external furnace, such as a steam engine.
ION - An atom or group of atoms that is electrically charged.