Proportional Thinking with Coulomb's Law

Proportional Thinking with Coulomb's Law

Force is PROPORTIONAL to charge. As the quantity of charge INCREASES, force INCREASES.

Relationship between charge and electrostatic force

Force in INVERSELY proportional to the square of the distance. As the distance between the charges INCREASES, force DECREASES.

Relationship between distance and electrostatic force

​Coulomb's Law Relationships

1. Variables in the problem that stay the same are represented with a 1

2. Variables that increase or decrease are represented with the factor of change

3. Ex. How would the electrostatic force change if the charge of one object is quadrupled?

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Proportional Thinking

Example.

How would the electrostatic force between two objects change if one of the charges triples?

​Try it out...watch the video to check your response!

Example.

How much stronger is the electrostatic force if the distance between two charged objects is cut in half?

​Try it out...watch the video to check your response!

Example.

How would the electrostatic force between charged objects change if they go from being 1m apart to 3m apart?

​Try it out...watch the video to check your response!

Example.

How would the electrostatic force between charged objects change if the magnitude of both objects triples and the distance doubles?

​Try it out...watch the video to check your response!

Multiple Choice

When distance increases, electrostatic force ____________; we call this relationship ____________ proportional

• decreases;directly
• decreases;inversely
• increases;inversely
• increases;directly

Multiple Choice

If the distance doubles, what happens to the force?

• Reduced by half
• Reduced by 1/4
• Stays the same
• Quadruples

Multiple Choice

Which setup of charged particles shown below has the two exert the most force on one another?

Multiple Choice

If each of the charges doubles, what happens to the force?

• Quadruples
• Doubles
• Stays the same
• Reduced by half