Larry, Jim,
Any one want to check my math?
I checked it, and Larry is right.
A half gallon of water (1893 milliliters), which has a specific heat of
roughly 4.19 joule per milliliter per kelvin (the actual value varies
slightly with temperature), heated for 5 minutes (300 seconds) with 1500
watts, would warm up by
1500 * 300 / 1893 / 4.19 = 56.7 kelvin,
which is the same as 56.7 degrees Celsius. Hardly enough to make it
boil, unless it was pretty warm to begin with!
Starting from typical tap temperature, and considering some loss that
ends up heating the kettle and producing some steam, the actual time
required for boiling would be somewhat between 7 and 8 minutes, assuming
the power is actually 1500 W and the water volume is actually half a
gallon - and that the water is pure, not mixed with some liquid that has
a lower specific heat! Now I don't think that anyone will boil a
water/glycol mix to make coffee, but it's very possible that the heater
actually is consuming more than 1500 W, or that the amount of water is
somewhat less than half a gallon.
This illustrates that cooling a legal limit amp with a bucket of water
under the operating desk is a satisfactory method for casual operation
in SSB, but won't cut it for a full weekend of RTTY contesting!
Manfred
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