Physics Review

The Law of Universal Gravitation and Coulomb’s Law for electrostatic forces are often compared. Which answer most completely describes the difference/s between the gravitational force and the electrostatic force?

• The gravitational force can only attract but the electrostatic force can attract or repel

• The gravitational force is much weaker than the electrostatic force

• The gravitational force is weaker and can only attract objects but the electrostatic force is strong and can both attract and repel

• The gravitational force occurs throughout the universe but the electrostatic force only occurs on Earth

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NGSS.HS-PS2-4

Two charged objects are held 1 meter apart from each other. Then they are moved to 2 meters apart. How is the electrostatic force and gravity force between them affected by this move?

• Both forces will be ¼ as strong after the move.

• Both forces will be ½ as strong after the move.

• Gravity will be ½ as strong and the electrostatic force will be ¼ strong.

• Gravity will be ¼ as strong and the electrostatic force will be ½ as strong.

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NGSS.HS-PS2-4

An inflated balloon which has been rubbed against a person’s hair is touched to a neutral wall and remains attracted to it. Which picture correctly represents the charge distribution on the balloon and the wall.

• Image A is correct because the top and bottom of the balloon have less charge.

• Image B is correct because the while there are still positive charges in the balloon, they are repelled by the positive charges in the wall

• Image C is correct because there is not enough charge in the balloon to completely repel all of the negative charges on the wall’s surface

• Image D is correct because the negative particles in the wall will be attracted to the positive charges on the other side of the balloon.

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NGSS.HS-PS2-4

A group of students are conducting an investigation about charging through the process of friction. The students rub two neutral materials together, and there is a transfer of electrical charge from one material to the other. What is the net electrical charge of the objects?

• The net electrical charge is positive as electrons are transferred from one material to the other.

• The net electrical charge is positive as protons are transferred from one material to the other.

• The net electrical charge remains neutral as electrons are transferred from one material to the other,

• The net electrical charge remains neutral as protons are transferred from one material to the other.

Tags

NGSS.HS-PS2-4

An uncharged balloon was hanging from the ceiling. A positively charged rod was brought close to, but never touching it, the balloon was attracted to the rod as shown. When the positively charged rod is removed and replaced with a negatively charged rod, what will the balloon do and why?

• The balloon will be attracted to the negatively charged rod because it has the opposite charge of the positively charged rod.

• The balloon will be attracted to the negatively charged rod because the charges will separate on the surface of the balloon.

• The balloon will be repelled by the negatively charged rod because it has the opposite charge of the positively charged rod.

• The balloon will be repelled by the negatively charged rod because the charges will separate on the surface of the balloon.

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

According to the Law of Conservation of Electric Charge, which scenario could NEVER occur?

• The total charge on an object change

• Net charge has been created or destroyed

• One object has more charge than another

• The total amount of charge on an object increases

What is potential difference?

• the difference in electric potential (Voltage) between the final and the initial location when work is done upon a charge to change its potential energy

• the difference in gravitational pull between the final and initial location when work is done upon a charge to change its potential energy

• the difference in resistance (R) between the final and the initial location when work is done upon a charge to change its potential energy

• the difference in current (I) between the final and the initial location when work is done upon a charge to change its potential energy

This process results in a transfer of electrons between two objects that are rubbed together.

• Conduction

• Induction

• Friction

This process involves the contact of a charged object to a neutral object.

• Conduction

• Induction

• Friction

A method used to charge an object without actually touching the object to any other charged object.

• conduction

• induction

• friction