jedovaty wrote:
I'm trying to wrap my head around how electric heat works..

Let's say there are two identical containers, empty, each has an identical electrical heat source, and a thermometer magically suspended right smack in the middle. We set the heat source so that both containers maintain a temperature of 400F.
Heat source = temperature controller or find a constant power level that maintains a temperature balance?

What happens if we take the heat source from one container and put it into the other? With the temperature in the container stay the same or increase?
If thermostatically controlled and if we're talking about the container now having two heat sources then as Dan stated, temp stays steady. If constant power level then temp goes up. If we're talking about the container with no heat source I'm afraid the temperature will drop quickly.

Would the above matter on how the heating source is set to maintain the temp? Whether voltage or amperage is reduced vs. one of those "on-off-on-off-on-off" infinite switches?
By voltage or amperage is reduced I'm assuming you're implying either a phase angle or PWM type of temperature controller versus a bimetal type infinite control. If an infinite switch is used and you leave the dial setting the same for both scenarios, the container with no heating element will still drop, the temperature in the one receiving the additional element will go up since an infinite switch can only maintain the duty cycle you set and does not maintain a temperature setpoint.

Thank you for the physics lesson :)
jano