Otherwise knowledgeable users are baffled by one silly question when confronted with an iMac: How do I turn the computer on? Where’s the power switch? It’s not a stupid question. Apple has hidden the power button cleverly where you can’t possibly see it. It’s also very difficult to feel the button because it is flush with the case. If you do look back there, it’s probably hidden behind the curve of the case.
Anyway, here it is on a Mid 2011 iMac. It’s been in a similar position for several years. Glad to help, and don’t worry, we won’t tell anyone you had to look here to find out to turn on a Macintosh.