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Physics lab question? Please help quickly?
Physics lab experiment question?
use your insulated cup (and some larger microwaveable container, if available) and your thermometer to determine the effective cooking power of a microwave oven for different amounts of water. Try to use 4 or 5 different amoutns of water spread over as wide a range of volumes as possible ( few tens of cc's to 5000 or more) design an expierment using whayt you know about thermal properties of water to design an experiment to test how much energy is transferred to the water in a given amount of time. from this measurement you can determine the actual power in watts that the microwave delivers to the water. how does the maximum cooking power you measure compare to the electrical power the microwave uses? based on your date, what amounts of water corresponded to the most efficient use of electrical power?
please help thank you very much.
The transfer of thermal energy to the water that under goes a temperature change, Tf - Ti , is found from the heat formula;
Q = MC(Tf - Ti)
So measure the temp. (in Celsius) before and after you microwave it and sub into the formula.
The power is the rate of energy transfer, so divide , Q , by the time you microwaved. Compare your experimental value of power, Q/t , with the wattage on the microwave. Probably in the back or underneath the machine.
C = specific heat of water. Look it up. Use units of, Joules/kg-degC.
M = mass of the water in kg. You can find that from density x volume. Be sure to change volume in cc to cubic meters and use density in kg/m^3.
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