Crank up some electricity
How much electrical power can You generate

Turn the crank and push and hold the switches one at a time
Can you. Light. Light bulb? Can you ring the chime?
Can you. Enough to power up all of the devices?
Notice that it is hardest to turn the crank as the switches are pressed and more power is used.
What is going on
The crank turns a belt that drives a motor. When you apply electricity to a motor it turns but if you mechanically turn a motor it becomes a generator that converts the mechanical energy back into electricity. Thisi is how a hybrid car, like a Prius, works. The more devices you turn on, the harder you have to crank because themorepower is needed. Notice how the lights barely glow if you crank slowly because the electrical power you are generating is low.

If you look inside you can see how the belt transfers the power from your cranking wheel to the motor using a belt and pulley mechanism.