Copy of Physics - Chapter 18 - Static Electricity

There are very large numbers of charged particles in most objects. Why, then, don’t most objects exhibit static electric effects?

• A. Most objects are neutral.
• B. Most objects have positive charge only.
• C. Most objects have negative charge only.
• D. Most objects have excess protons.

Can an insulating material be used to charge a conductor? If so, how? If not, why not?

• A. No, an insulator cannot charge a conductor by induction.
• B. No, an insulating material cannot charge a conductor.
• C. Yes, an uncharged insulator can charge a conductor by induction.
• D. Yes, a charged insulator can charge a conductor upon contact.

True or false—A liquid can be an insulating material.

• A. true
• B. false

If you dive into a pool of seawater through which an equal amount of positively and negatively charged particles is moving, will you receive an electric shock?

• A. Yes, because negatively charged particles are moving.
• B. No, because positively charged particles are moving.
• C. Yes, because positively and negatively charged particles are moving.
• D. No, because equal amounts of positively and negatively charged particles are moving.

True or false—The high-voltage wires that you see connected to tall metal-frame towers are held aloft by insulating connectors, and these wires are wrapped in an insulating material.

• A. true
• B. false

By considering the molecules of an insulator, explain how an insulator can be overall neutral but carry a surface charge when polarized.

• A. Inside the insulator, the oppositely charged ends of the molecules cancel each other.
• B. Inside the insulator, the oppositely charged ends of the molecules do not cancel each other.
• C. The electron distribution in all the molecules shifts in every possible direction, leaving an excess of positive charge on the opposite end of each molecule.
• D. The electron distribution in all the molecules shifts in a given direction, leaving an excess of negative charge on the opposite end of each molecule.

A dust particle acquires a charge of −13 nC. How many excess electrons does it carry?

• A. 20.8 × 10^−28 electrons
• B. 20.8 × ^−19 electrons
• C. 8.1 × 10^10 electrons
• D. 8.1 × 10^19 electrons

Two identical conducting spheres are charged with a net charge of +5.0 q on the first sphere and a net charge of −8.0 q on the second sphere. The spheres are brought together, allowed to touch, and then separated. What is the net charge on each sphere now?

• A. −3.0q
• B. −1.5q
• C. +1.5q
• D. +3.0q

Two plastic spheres with uniform charge repel each other with a force of 10 N . If you remove the charge from one sphere, what will be the force between the spheres?

• A. The force will be 15 N.
• B. The force will be 10 N.
• C. The force will be 5 N.
• D. The force will be zero.

What creates a greater magnitude of force, two charges +q a distance r apart or two charges – q the same distance apart?

• A. Two charges +q a distance r away
• B. Two charges −q a distance r away
• C. The magnitudes of forces are equal.