AP Physics 2: Electrostatics and Charging

Reorder the following to show the progression of steps in Charging by Induction.

• 
• 
• 
• 
• 

Tags

NGSS.HS-PS3-5

A solid conducting sphere is given a positive charge Q. How is the charge Q distributed in or on the sphere?

• It is concentrated at the center of the sphere.

• It is uniformly distributed throughout the sphere.

• Its density decreases radially outward from the center.

• Its density increases radially outward from the center.

• It is uniformly distributed on the surface of the sphere only

Answer explanation

In solid conductors, free electrons move to the surface when a charge is applied, leaving a net charge distributed uniformly on the surface. Hence, when a positive charge Q is given to a solid conducting sphere, it is uniformly distributed on the surface of the sphere only.

The electrostatic interaction between three objects is as shown. Which of the following is a possible combination of the correct charges on each? Choose all answers.

• A: Positive

  B: Positive

  C: Positive

• A: Neutral

  B: Positive

  C: Positive

• A: Negative

  B: Positive

  C: Negative

• A: Positive

  B: Neutral

  C: Positive

• A: Neutral

  B: Negative

  C: Negative

Answer explanation

The question asks for the possible combination of charges on three objects based on their electrostatic interaction. The valid combination can be 'A: Positive, B: Positive, C: Positive' or 'A: Neutral, B: Positive, C: Positive' because like charges repel each other and unlike charges attract. Also, a neutral object can be attracted by a charged object.

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

During a physics lab, a plastic strip was rubbed with cotton and became positively charged. The correct explanation for why the plastic strip becomes positively charged is that ...

• the plastic strip acquired extra protons from the cotton.
  

• the plastic strip acquired extra protons from the charging process 

• protons were created as the result of the charging process
  

• the plastic strip lost electrons to the cotton during the charging process 

Answer explanation

The question asks why a plastic strip becomes positively charged when rubbed with cotton. The correct answer is that the plastic strip lost electrons to the cotton during the charging process. This is due to the triboelectric effect where certain materials attract the electrons of other materials when rubbed together, resulting in a positive charge for the material losing electrons, in this case, the plastic strip.

Tags

NGSS.HS-PS1-2

Insulators are different than conductors in that insulators ____.

• do not contain electrons or protons 

•  do not contain any charge

• have a weaker affinity for electrons 

• do not allow charge to freely move 

Answer explanation

The question asks about the difference between insulators and conductors. Insulators are materials that resist the flow of electric charge, while conductors allow charge to move freely. The correct option is 'do not allow charge to freely move' as it correctly defines the property of insulators.

Consider the conduction charging shown. 

• Electrons move from the insulating stand into the sphere.

• Protons move from the bar into the sphere.

• Electrons move from the charged metal bar into the sphere.

• Protons move from the sphere into the negatively charged bar.

Answer explanation

In conduction charging, when a charged metal bar contacts the sphere, the electrons from the bar will move into the sphere due to the repelling force of negative charges in the bar. This explains why 'Electrons move from the charged metal bar into the sphere' is the correct answer.

Tags

NGSS.HS-PS3-5

A glass rod becomes positively charged when it is rubbed with silk. This net positive charge accumulates because the glass rod

• gains electrons

• loses electrons

• gains protons

• loses protons

Answer explanation

A glass rod becomes positively charged by losing electrons when rubbed with silk. This is due to the triboelectric effect, where certain materials will either gain or lose electrons when in contact with another material. In this case, the glass rod is losing electrons to the silk, leaving a net positive charge on the rod.

Tags

NGSS.HS-PS3-5

When a plastic rod is rubbed with wool, the wool acquires a positive charge because

• protons are transferred from the wool to the rod

• protons are transferred from the rod to the wool

• electrons are transferred from the rod to the wool

• electrons are transferred from the wool to the rod

Answer explanation

When a plastic rod is rubbed with wool, the wool acquires a positive charge. This is because electrons, which have a negative charge, are transferred from the wool to the rod during the rubbing process. The wool then obtains a positive charge due to the loss of negatively charged electrons.

Electrostatic force F exists between two point charges. If the both charges are doubled, the force between the charges will be

• F

• 4F

• 2F

• F/4

Answer explanation

The electrostatic force between two charges is given by Coulomb's Law, which states that the force is directly proportional to the product of the charges. If both charges are doubled, the product of the charges becomes four times as large, hence the force becomes four times as large, or '4F'.

Tags

NGSS.HS-PS2-4

Like charges __________ and opposite charges ________.

• attract, repel

• attract, attract

• repel, attract

• repel, repel

Answer explanation

The question asks what happens when like and opposite charges interact. According to the laws of physics, like charges repel each other and opposite charges attract. This is why the correct answer is 'repel, attract'.