All of us see the upright dash in middle of an O daily in our lives on most of the gadgets we use. Most of the devices requiring power supply like mobile, sound system computer etc display this symbol. This is not just a symbol for power But much more.
Logic between symbol of power
The symbol I and O stand for on and off. Before they appeared like this, power was represented by two switches with on and off written over them. If you pay attention closely you’ll notice that the switch with semi broken O and stands for a switch with on and off power with sleep or standby mode. This symbol is standardised as IEC 5009, IEC means international electrical commission.