electrostatics

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 

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 

 A balloon is rubbed against a student's hair and then touched to a wall. The balloon sticks to the wall due to

• magnetic forces between the particles of the balloon and the particles of the wall
• electrostatic forces between the particles of the balloon and the particles of the wall
• magnetic forces between the particles of the wall
• electrostatic forces between the particles of the balloon

Tags

NGSS.MS-PS2-3

A negatively charged plastic comb is brought close to, but does not touch, a small piece of paper. If the comb and the paper are attracted to each other, the charge on the paper

• must be positive
• must be negative
• may be neutral or negative
• may be neutral or positive 

Two electrically charged identical-sized metal spheres, A (charge of -4) and B (charge of +8). If the spheres are brought into contact, which sphere will have a net gain of electrons?

• both A and B
• neither
• only A
• only B

Two electrically neutral metal spheres, A and B, on insulating stands are placed in contact with each other. A negatively charged rod is brought near, but does not touch the spheres, as shown in the diagram below. How are the spheres now charged?

• A is positive and B is positive.
• A is negative and B is positive.
• A is positive and B is negative.
• A is negative and B is negative.

Tags

NGSS.MS-PS2-3

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

Tags

NGSS.MS-PS2-3

Which of the following is a false statement about electrostatic force.

• Bringing charges closer together strengthen the force.
• The electrostatic constant remains the same.
• The values of the two charges is always the same.
• Electrostatic force can be attractive or repulsive

An electrostatic force of magnitude F exists between two metal spheres having identical charge q. The distance between their centers is r. Which combination of changes would produce no change in the electrostatic force between the spheres?

• doubling q on both spheres while halving r
• doubling q on one sphere while halving r
• doubling q on one sphere while doubling r
• doubling q on both spheres while doubling r

Two similar metal spheres, A and B, have charges of +2.0 x 10^-6 coulomb and +1.0 x 10^-6 coulomb, respectively. The magnitude of the electrostatic force on A due to B is 4.0N newtons. What is the magnitude of the electrostatic force on B due to A?

• 2.0N
• 4.0N
• 8.0N
• 1.0N