Why do different connectors have different shapes and sizes?

Answer 1

In one way that is like asking why clothes or garden tools, buildings, Musical Instruments, cars, trucks, planes, ships, etc. have different shapes and sizes... The reason is because the diverse uses to which they are applied require them to be made in different shapes and sizes.

But it is not only as simple as that: some electrical items can become very dangerous indeed - to people, animals, vehicles, buildings, etc - if they are hooked-up to their electrical supplies incorrectly. Some electrical items can catch on fire or explode if they are connected to the wrong voltage or the wrong type of electrical supply. It makes no difference if some wrong connections were not done deliberately but "just by accident", the end result would be the same: disaster.

So the idea of using different shapes and sizes of connectors to help people avoid making bad hook-ups and having accidents was invented by the same brilliant engineers who discovered how to make batteries, generators, light bulbs, electric motors, computers and all the other wonderful electrical things many of us now take for granted in our everyday lives.

By inventing different shapes and sizes of connectors an excellent and yet very simple way was found for us all - even if we know nothing about electricity - to make the right connections easily "first time". That same clever invention makes it much more difficult for us to make any dangerous bad hook-ups "just by accident" because the plugs or connectors for a particular appliance or electrical device will only fit into the correctly-matching sockets or connectors which are intended for use with that particular item, and won't fit into any sockets or connectors which do not match.

A further very real benefit of having many different shapes and sizes - and colors - of connectors, plugs and sockets is that, for any given electrical appliance or system of components - such as the many different connections that are needed inside a house - for phones, television aerials, cable services, computers and their peripherals (keyboard, mouse, monitor, printer, scanner, modem, speakers), small electrical appliances, large electrical appliances, etc. - it is very easy for anyone to see exactly which wire or cable needs to go into which outlet without always having to study a User Guide first. When there are different shapes and sizes of connectors you don't even have to be trained how to use complicated electrical wiring diagrams and test equipment.