AP Physics Electrostatics

Two electrons are 1 nm apart. Estimate and compare the gravitational force between the electrons to the electric force between the electrons.

• The gravitational force is much stronger.

• The two forces are about the same magnitude.

• The electric force is much stronger.

• There is no gravitational force between them.

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NGSS.HS-PS2-4

The gravitational force be confidently ignored when dealing with atomic size particles because:

• It is many orders of magnitude greater than the electric force.

• It is many orders of magnitude smaller than the electric force.

• There is no gravitational attraction between atomic masses.

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NGSS.HS-PS2-4

Two small aluminum foil balls of equal mass, A and B, have electric charges +q and +3q, respectively. Compare the magnitude of the electric force that the foil ball A exerts on B to the magnitude of the electric force that foil ball B exerts on A.

• It is 3 times smaller.

• It is the same.

• It is 3 times larger.

• Not enough information is given to determine the answer.

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NGSS.HS-PS3-5

The electric potential energy of a system with two charged point-like objects is:

• Proportional to (q1^2).

• Proportional to (G).

• Proportional to (1/r).

• Proportional to (1/r²).

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NGSS.HS-PS2-4

If two charged point-like objects have electric potential energy U, and the distance between them is doubled, the electric potential energy is:

• Quartered

• Halved

• Doubled

• Quadrupled

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Based on this graph of the electric potential energy of two objects, what can you conclude about those two objects?

• The two objects have the same type of charge.

• The two objects have unlike charges.

• Only one of the two objects is charged.

• There isn't enough information in the graph to reach any of these conclusions.

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NGSS.HS-PS2-4

Which of the following processes is a result of electric forces?

• Hair standing on end when a person touches a Van de Graaff generator

• Toner particles creating an image in a photocopier

• A Wimshurst machine creating sparks in the air

• All the answers

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A plastic rod is rubbed with a piece of wool. During the process the plastic rod acquires a negative charge and the wool

• acquires an equal positive charge

• acquires an equal negative charge

• acquires less in magnitude positive charge

• acquires less in magnitude negative charge

A neutral conducting sphere A is placed on an insulating table. Which of the following will cause the sphere to gain positive charge?

• Touch the sphere with a negatively charged rod

• Touch the sphere with a positively charged rod

• Bring a negatively charged rod near the sphere and briefly touch the sphere with a grounding wire

• Bring a positively charged rod near the sphere and briefly touch the sphere with a grounding wire

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Two electrons are separated by a distance r. Which of the following statements is correct?

• There is an attractive electrostatic force between the electrons

• There is a repulsive electrostatic force between the electrons

• The gravitational force between the electrons much greater than electrostatic force

• The electrostatic force is much greater than gravitational force

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