How do computers/mobiles/tablets know the time even when they’re switched off and not connected to the internet?
In: 0
Computers, laptops, phones, and tablets still have a small circuit that’s on, even when they’re off. This circuit is basically responsible for keeping the clock running. On desktop computers, this is typically powered by a CR2032 battery on the motherboard. On laptops, smartphones, and tablets, this is often a rechargeable battery that is smaller than the main battery.
What the actual source of the (seemingly universal) “correct” time?
They have clocks in them, just like an electronic wrist watch. Those clocks still keep time even when the device is turned off. A tablet or other mobile device probably still uses the main battery for this, but a computer usually has a small watch battery on the motherboard to maintain this power.