Electrostatics

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 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

 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

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

A positively charged rod is held near the knob of a neutral electroscope. What best describes what will happen to the leaves?

• the leaves will spread apart and be positive
• the leaves will spread apart and be negative
• the leaves will stay closed and be positive
• the leaves will stay closed and be negative

Which net charge could be found on an object?

• 4.8 x 10^-19 C
• 1.8 x 10^-19 C
• 3.0 x 10^-19 C
• 2.8 x 10^-19 C

Metal sphere A has a charge of +12 elementary charges and identical sphere B has a charge of +16 elementary charges. After the two spheres are brought into contact and separated, the charge on sphere A is

• +14 elementary charges
• +28 elementary charges
• +2 elementary charges
• -2 elementary charges

Three charged metal spheres, X, Y, and Z, are on insulating stands. All three spheres are simultaneously brought into contact with each other and then returned to their original positions.
Which statement best describes the charge of the spheres after this procedure is completed?

• All the spheres will end up with the same charge
• All the spheres are neutral
• Sphere Y has a greater charge than spheres X or Z
• Each sphere retains the same charge that it had originally

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