What Does The O And I Mean On A Switch?


Is There Any Meaning to The O And I On A Light Switch?


Answers ( 2 )


    What exactly is it, and what is it used for?

    The power button is a round or square button capable of turning an electronic device on and/or off. Almost all electronic devices have power buttons or switches. 

    A device typically turns on when the button is pressed and off when the button is pressed again. 

    A hard-type power button is mechanical. You can feel a click when you press it and usually see a difference in depth when the switch is on versus when it is not. 

    A soft-type power button, which is much more common, is electrical and looks exactly the same when the device is on or off. 

    Certain older devices feature a power switch capable of accomplishing the same thing as a hard-guy power button. A movement of the switch in one direction will start the device, and a movement in the opposite direction will turn it off.


    You can find these kinds of buttons on printers, photocopiers, and plugs, but many people (including me until I did some research) don’t know why the “O” and “|” symbols are there. Well, it’s easy to see why.

    The first symbol, “O,” shows that the switch is “off.” The second symbol, “|,” shows that the switch is “on.” These ways of showing things come from the binary code used in electronics, where the number 0 means “off” and the number 1 means “on.” This idea has changed over time, and new symbols have been made, like the bar inside the circle, which shows how both ideas fit together.
    The “Rest/Stand-by” command was also made by breaking the top of the circle and putting part of the bar into it. It’s also important to note that this command is used wrongly in many of the devices we use today, since it does “on” and “off” in the wrong way.


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