A 100-watt lightbulb uses 1 kilowatt-hour of electrical energy when it is on for ten hours. How much energy does
a 25-watt lightbulb use when it is on for ten hours?

Energy = 0.25 kilowatt-hour

Explanation:

Given the following data;

Power = 25 Watts

Time = 10 hours

Power can be defined as the energy required to do work per unit time.

Mathematically, it is given by the formula;

To find the energy consumed;

Energy = power * time

Substituting into the formula, we have;

Energy = 25 * 10

Energy = 250 Watt-hour

To convert to kilowatt-hour, we would divide by 1000;

Energy = 250/1000

Energy = 0.25 kilowatt-hour

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

total distance/total time

(85 + 82)/(5+3)

167/8

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