# Electricity: Electric Ciruits

## Electric Circuits: Audio Guided Solution

#### Problem 10:

Determine the amount of electrical energy (in J) used by the following devices when operated for the indicated times.
a. Hair dryer (1500 W) - operated for 5 minutes
b. Electric space heater (950 W) - operated for 4 hours
c. X-Box video game player (180 W) - operated for 2 hours
d. 42-inch LCD television (210 W) - operated for 3 hours

## Audio Guided Solution

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## 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.