# Electricity: Static Electricity

## Static Electricity: Audio Guided Solution

#### Problem 22:

Mr. H inflates a 1.4-gram balloon and charges it negatively by rubbing it on his head. He then rubs a plastic tube with animal fur to impart a charge of -4.3x10-8 C. By holding the plastic tube at a position of 12 cm below the balloon, he is able to levitate the balloon. Consider the two objects to be point charges and determine the quantity of charge upon the balloon.

## 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; record them in an organized manner. A diagram is a great place to record such information. Equate given values to the symbols used to represent the corresponding quantity - e.g., Q1 = 2.4 μC; Q2 = 3.8 μC; d = 1.8 m; Felect = ???.
• 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.