GCSE Computing/Computing hardware/Introduction to Binary Logic/Binary logic/On Off or High Voltage Low Voltage
In many cases we say that binary is shown by whether a wire (or other electrical signal) is on or off. You should understand that this is not literally true. What a computer is really detecting is whether the signal is high or low voltage. Sometimes you will see things referring to this high or low voltage instead of on or off. It is exactly the same idea, just explained slightly differently.
We also talk about a current in a wire. This is often absolutely what is happening, but you need to understand that the wire is not like a normal wire you'd see attached to something: it is absolutely tiny, etched inside a chip. The widths are constantly getting narrower, but are measured in nanometers, where one nanometer is one billionth of a metre. These wires are far too small to be seen with a microsocope.