Electrostatics Revision

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

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.

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

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

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

Metal sphere A has a charge of -2 units and an identical metal sphere, B, has a charge of -4 units. If the spheres are brought into contact with each other and then separated, B will _____

• gain 1 electron
• lose 1 electron 
• gain 3 electrons
• lose 3 electrons