# Electricity: Electric Ciruits

## Electric Circuits: Audio Guided Solution

#### Problem 18:

An overhead high voltage (4.0x105 V) power transmission line delivers electrical energy from a generating station to a substation at a rate of 1500 MW (1.5x109 W). Determine the resistance of and the current in the cables.

## 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.