One of the most common symbols is on the on/off switch to your telly. According to an explainer by cracked.com on Facebook, ...

The power symbol, which can still be seen on nearly all modern PCs and laptops, originated in the 1950s. At the time, devices were still operated using physical switches that had “on” and ...

A circuit has to have a power source and that is often a cell ... to draw the + and – symbols but they can be helpful. The switch symbol (off) has a line at an angle to show the circuit has ...

First we need power, man – this symbol here is a cell ... Don’t forget the switch – we’ll set it up so if someone treads on it, the switch will close, setting off our alarm!