physics

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What power - in Watt-hours - is needed at home on your standard 115 V circuit to run: (a) a
10 A air conditioner for one hour to completely cool off your room, or (b) a 3 A electric fan to
keep a constant flow of air over you for five hours? (c) Which is more efficient for you to use?
and (d) Why would your choice be more efficient?

  • physics -

    (a) A 115 V that draws 10 A consumes up to 1.150 kilowatts. In one hour, that is 1.15 kwh. This assumes a "power factor" of 1. The meaning of power factor in AC circuits should have been explained to you.
    (b) A 115 V, 3A fan consumes 1.725 kwh in five hours.

    Multiply both by 1000 for watt-hours.

    (c) They should define efficiency. A fan will not cool you if the humidity is 100%. The A/C will be much more comfortable. If the A/C is only on for one hour, the room will heat up again, unless the A/C is cycling on and off during the five hours.

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