Electricity: Electric Ciruits
Electric Circuits: Audio Guided Solution
During the Christmas season, Sel Erbate uses the equivalent of 45 strings of 100 mini-bulbs to light the inside and outside of his home. Each 100-bulb string of lights is rated at 40 Watts. The average daily usage of the strings is 7 hours. The lights are used for approximately 40 days during the holiday season.
a. Determine the resistance of each string of lights. Each is powered by 110-volt outlet.
b. Determine the energy consumed (in kW•hr) by the lights over the course of 40 days.
c. If Sel pays 12 cents/kW•hr for electrical energy, then what is the total cost of Christmas lighting for a single season?
Audio Guided Solution
Habits of an Effective Problem Solver
Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
Identify the known and unknown quantities and record them in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., ΔV = 9.0 V; R = 0.025 Ω; I = ???.
Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
Identify the appropriate formula(s) to use.
Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.
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