Older freezers developed a coating of ice inside that had to be melted periodica

Question

Older freezers developed a coating of ice inside that had to be melted periodically; an electric heater could speed this defrosting process. Suppose you're melting ice from your freezer using a heating wire that carries a current of 5.2 A when connected to 120 V.

a) What is the resistance of the wire?
(I found that this was 23 )

Older freezers developed a coating of ice inside that had to be melted periodically; an electric heater could speed this defrosting process. Suppose you're melting ice from your freezer using a heating wire that carries a current of 5.2 A when connected to 120 V. a) What is the resistance of the wire? (I found that this was 23 omega) b) How long will it take the heater to melt 840 of accumulated ice at -10 degree C? Assume that all of the heat goes into warming and melting the ice, and that the melt water runs out and doesn't warm further.

Explanation / Answer

a) Ohm's law. V=I*R turns to R= V/I. b) Work = Power*Time =(I*V)*Time To melt the ice, you need to heat it to melting temp then melt it. You need to apply enough work to melt it. work to heat= mass * heat capacity * temperature difference work to melt= mass *fusion heat capacity Sum the two works, divide by I*V. That's the time it'll take. t=(Wm+Wh)/(I*V)

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