# 7 - I’d put my money on the sun and solar energy What a...

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I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that. Thomas Edison, 1931

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Arizona State University SES 194 Energy in Everyday Life Frank Timmes [email protected] Power & Energy Scales
So far we have discussed work and energy. In our everyday lives, not only how much work is done, but fast it is done, is also relevant. A 1200 watt toaster singes bread twice as fast as a 600 watt toaster.

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Power as the energy transferred (work done) divided by the time needed to do the work. SRZHU = HQHUJ\ WLPH WR GR WKH ZRUN Power is the rate at which energy changes with time. Power is measured in Watts, one Watt being the power needed to use one joule of energy in one second.
Since power = energy/time, we can also say energy = power × time. This is what the electric company measures, kilowatt-hours, for your monthly bill.

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10 -38 10 -36 10 -34 10 -32 10 -30 10 -28 10 -26 10 -24 10 -22 10 -20 10 -18 10 -16 10 -14 10 -12 10 -10 10 -08 10 -06 10 -04 10 -02 1 Joule 10 +02 10 +04 10 +06 10 +08 10 +10 10 +12 10 +14 10 +16 10 +18 10 +20 10
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