Conductors and Insulators

If objects X and Y attract each other, which of the following will be FALSE?

• 1. X has positive charge and Y has negative charge.

• 1. X has negative charge and Y has positive charge.

• 1. X and Y both have positive charge.

• 1. X is neutral and Y has a charge.

What will be the net charge on an object which attracts neutral pieces of paper but repels a negatively charged balloon?

• Negative

• Positive

• Neutral

• Cannot be dtermined

In an experiment, a student runs a comb through his hair several times and brings it close to small pieces of paper. Which of the following will he observe?

• 1. Pieces of paper repel the comb.

• 1. Pieces of paper are attracted to the comb.

• 1. Some pieces of paper are attracted and some repel the comb.

• 1. There is no attraction or repulsion between the pieces of paper and the comb.

Some students experimenting with an uncharged metal sphere want to give the sphere a net charge using a charged aluminum pie plate. Which of the following steps would give the sphere a net charge of the same sign as the pie plate?

• 1. bringing the pie plate close to, but not touching, the metal sphere, then moving the pie plate away.

• 1. bringing the pie plate close to, but not touching, the metal sphere, then momentarily touching a grounding wire to the metal sphere.

• 1. bringing the pie plate close to, but not touching, the metal sphere, then momentarily touching a grounding wire to the pie plate.

• 1. touching the pie plate to the metal sphere.

When the balloon is brought closer to the sphere, there will be a redistribution of charges. What is this phenomenon called?

• Induction

• Conduction

• Polarization

• Electrostatic repulsion

When the balloon is brought closer to the sphere, there will be a redistribution of charges. What will be the net charge on the sphere?

• negative

• zero

• positive

• 1. It can be positive or negative depending on the material.