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Figuring out a stove top temperature using boiling water

by frikk
Tags: boiling, figuring, stove, temperature, water
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frikk
#1
Feb15-09, 04:15 PM
P: 1
hey everyone,
how funny it is that i have a real life problem that fits nicely into a physics problem. I am going to start roasting my own coffee on my stove top. I need 350 constant heat. The problem is that my stove top just has a dial, and no temperatures (and i, conveniently, have no thermometer). I know this about my stove:
* the control dial reads 1-6, and 'high', with a half setting in between all (.5, 1.0, .. 6.0, 6.5, high, high.5)
* 5.5 - 6.5 boil water (as does high)
* 'high' is not actually a 7.0, it is actually just 'maximum voltage' - as hot as it will go. I know this because one of my burners does not boil water at 6.5, but boils *really fast* at 'high'.

How might I find out the temperature of my stove top at 'high'? Ideally I need 350F (176C). I'm rusty on my ideal gas laws and thermodynamics. Any helpful hints? I'm thinking of measuring how long it takes water to boil on various settings (constant water volume with a lid).

Of course I could also look at the electrical properties of the stove, specific heat of the ceramics and material resistance, etc. for a theoretical maximum surface temperature. I suppose this could also be a viable, but a bit more tedious experimentally, route to take as well.

... or now that I think of it I could probably find the pdf of the stove's user manual on the internet (its really old, so it'd be some work). Boo to this idea! :)
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confinement
#2
Feb15-09, 09:40 PM
P: 192
The smoke point of butter is 350F, or you could use vegetable oil with smokepoint 325F.
russ_watters
#3
Feb15-09, 10:49 PM
Mentor
P: 22,313
You probably want to use the oven, not the stove. The stove gets much hotter than 350 F and it is very difficult to control the temperature of something sitting on it precisely because it is a heat flow problem, not a constant temperature, no heat transfer condition like an oven.

Ie, the fact that you can't boil water with a setting of 6.5 does not mean the burner is less than 212F, it just means it doesn't transfer heat fast enough to keep the water above 212F. You also will find that different amounts of water will boil at different settings on the stove.

Finally, stoves (as the above would imply) are not rated according to temperature, as temperature is pretty meaningless, they are rated for power. Generally, 2.5 kW is a pretty typical large burner.


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