switching between 2 sockets on a timer

[califauna]

So you have a 2800W (240v) kettle, and you want to drive it at 12volts. Well I get 7watts from the element, so it will take a while to boil the water.

The specific heat of water is 4.19J/gK.

1W = 1 joule/sec, so a 2800W kettle delivers 2800 per second, and a 7W one delivers 7 per second.

If we assume 1l of water to be raised by 90°C we need to put in 377,100 joules (assuming no heat losses during the process).

So with that assumption (which will be false in practice), a 2800W kettle will do it in 135 seconds. In practice a bit longer, but not much, as heat will be going in much faster than it is being lost,

A 7W one will take 15 hours. In practice I'd wager that "never" would be what happens.

Agreed. It might be feasible to maintain a certain temperature of water rather than heat it up in the first place, but I suspect with that kind of heating power, even the temperature it could maintain water at wouldnt be that great. Probably fall well below boiling temperature.

 

[Mursal]

A 7W one will take 15 hours. In practice I'd wager that "never" would be what happens.

Thanks Ban All Sheds for that nugget of wisdom.
My Science teacher said that a joule was the same amount of energy as it took to wiggle your big toe (dam all). Can you confirm the truth in this statement?