10.1 Exploring Static Charges Key Concepts: (Page 410)

Static Charge (static electricity) is an electric charge that tends to stay on an object’s surface. Friction can cause static charge when object made from different material rub together. Protons are positively charged, and electrons are negatively charged.

Any net charge on a solid object results from the transfer of electrons between it and another object. An object with more electrons than protons has a negative charge. An object with fewer electrons than protons has a positive charge. An object with equal numbers of electrons and protons is neutral. An electrostatic series describes how strongly different materials hold on to their electrons.

In electrical insulators, such as most non-metals, electrons cannot move easily between atoms. In electrical conductors, such as metals, electrons can move easily from one atom to another. A ground is connected to Earth and can supply a very large number of electrons from, a charged object.

Charging by Friction: Electricity is a form of energy that results from the interaction of charged particles, such as electrons and protons. The word “static” means stationary, or not moving. 2. What does static charge or static electricity mean? Static charge or static electricity refers to an electric charge that tends to stay on the surface of an object, rather than flowing away quickly.

3. Describe a way where static charges can build up on objects. One way where static charges can build up on objects is when they are rubbed together as in clothes in a dryer. Examples: Walking on a carpet on a dry winter day, rubbing a balloon against a sweater, and combing your hair with a comb.

4. What happens when an object becomes charged by friction? When an object becomes charged by friction, one material has a stronger attraction to electrons than another material, and therefore pulls electrons off the materials that have weaker attraction to electrons.

5. Explain how to use the electrostatic series by using examples. The electrostatic series is used to determine whether the charges on two materials, after they are rubbed together, are positive or negative. The materials with atoms that have a stronger hold on electrons ends up with a negative charge. The other material whose atoms have a weaker hold on electrons, loses its electrons to the first material and becomes positively charged.

5. Copy down Table 10.1 Glass Human Hair Nylon, Wool Fur Silk Cotton Lucite(a clear plastic) Rubber Balloon Polyester Foam Grocery Bag (low density polyethelene) Ebonite (a hard form of rubber)

6. When you comb your hair with plastic comb, which object, the hair or the comb, holds on to its electrons more tightly? What is the charge on this object? A comb holds on to its electrons tightly. A comb becomes negatively charged after combing your hair.

7. If leather is rubbed with polyester, the polyester becomes negatively charged. Would you place leather above or below polyester in an electrostatic series? I would place the leather above polyester because objects on top of the electrostatic series tend to have weak hold on electrons.

Bounce sheets used in clothes dryers 8. List consumer products available in the market that will help eliminate static on clothes and other materials. Bounce sheets used in clothes dryers Liquid clothes softeners (fabric softner) that

Insulators and Conductors: 9. Compare the following terms; conductor, insulator and semiconductor. Give two examples of each. Conductor- a material in which electrons can move easily from one atom to another (ex. copper, aluminum) Insulator- a material in which electrons cannot move easily from one atom to another (ex. wood, plastic, rubber) Semiconductor-A material in which electrons can move fairly well between atoms (ex. silicon).

10. Is water a conductor or insulator? What about dry air? Explain. Pure water is a good insulator. Water from a faucet is a fairly good conductor because of all the dissolved substances. Dry Air is a good insulator but moist air is a fair conductor.

11. Why is grounding electrical equipment very important? Grounding electrical equipment is very important because when there is an electrical surge, excess electrons will be removed. This will prevent electrical shocks and fires.

12. Draw the symbol for ground.