AP Physics 1 : Electric Force Between Point Charges

Study concepts, example questions & explanations for AP Physics 1

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Example Questions

Example Question #11 : Electric Force Between Point Charges

Two electric charges are placed  apart, where  and .

What is the magnitude of force between them? Is it replusive or attractive?

Possible Answers:

Correct answer:

Explanation:

The force between the two charged particles is proportional to the product of their charges, according to Coulomb's Law. Whether the force is attractive or repulsive depends on the signs of the charges. Like signs will repel while opposite signs will attract.

Using Coulomb's Law to find the magnitude of the charge:

Therefore, the magnitude of the force has been discovered. Finally, since the signs are opposite ( and ), the force is attractive. Therefore the answer is:

Example Question #12 : Electric Force Between Point Charges

Which of the following pairs of charges would exhibit the most electrostatic repulsive force?

Possible Answers:

 charge and  charge  apart

 charge and  charge  apart

 charge and  charge  apart

 charge and  charge  apart

 charge and  charge  apart

Correct answer:

 charge and  charge  apart

Explanation:

The correct answer is the  charge and  charge  apart.

This results in the largest repulsive force according to the following equation:

 is the repulsive force,  is the magnitude of the charge,  is the distance between the charges and  is Coulomb's constant.

 and  charges placed  apart provides the greatest repulsive force.

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