BASIC ELECTRICITY

1. BASIC ELECTRICITY

2. Interest Approach • Have students make a list of their 10 favorite things to do. After they are finished with their list, have them circle the things that involve electricity. Remind them that batteries are also a source of electrical energy. This will get students thinking about the role electricity plays in their everyday lives and how important it is to them.

3. Student Learning Objectives: Instruction in this lesson should result in students achieving the following objectives: • 1 Define electricity, and explain different types of electricity. • 2 Explain how electricity is produced. • 3 Explain how electricity travels. • 4 Explain the difference between conductors and insulators. • 5 Explain circuits, and describe the difference between an open circuit and a closed circuit. • 6 Identify basic electrical safety tips.

4. Terms. The following terms are presented in this lesson (shown in bold italics): • Circuit • Closed circuit • Conductor • Current • Electricity • Electron • Insulator • Matter • Neutron • Open circuit • Proton • Speed of light • Transformer • Voltage

5. OBJECTIVE 1: Define electricity, and explain different types of electricity. • I. Electricity is a part of nature. It is all around us. We cannot see electricity, but we can see its effect, such as light and heat. Electricity plays a vital role in the lives of people. It is a necessary tool in our modern agricultural industry.

6. OBJECTIVE 1 continued • A. Electricity is a form of energy produced by the movement of electrons. • 1. Matter is anything that takes up space or has mass. Everything you can touch is made of matter. All matter is made up of atoms.

7. OBJECTIVE 1 continued • 2. An atom has a center, called a nucleus. The nucleus has at least one proton and one neutron. At least one electron travels around the nucleus at a fast rate of speed. • a. A proton is a particle with a positive (+) charge. • b. A neutron is an uncharged, neutral particle. • c. An electron is a particle with a negative (–) charge.

8. OBJECTIVE 1 continued • When the balance of protons and electrons is changed by an outside force, an atom may gain or lose an electrical charge. This movement of charge is what we refer to as electricity.

9. What does copper wire and magnets have to do with Electricity? In September of 1831, Michael Faraday made the discovery of Electromagnetic Induction. Faraday attached two wires to a disc and rotated the disc between the opposing poles of a horseshoe magnet creating an electric current.

10. Electricity • Electricity is the flow of electrons in a conductor. • The electrons must have a path to and from its source. • This path is called a circuit.

11. OBJECTIVE 1 continued • B. There are two basic types of electricity: static and current. • 1. Static electricity stays in one place and doesn’t move like current electricity. • Electrons DON’T move • An example of static electricity is the tiny spark or shock between two people after they walk or rub their feet across the carpet.

12. OBJECTIVE 1 continued • 2. Current electricity is a flow of electrical charge through a substance that conducts electricity. Two kinds of current electricity are used: • a. In direct current (DC) electricity, the electrons flow in one direction. • This type of current is usually produced by batteries. • b. In alternating current (AC) electricity, the electrons flow in alternating directions and the direction of the current is reversed many times each second. • AC electricity comes from power lines.

13. Electrical Service • Electrical service begins with a power source, which is usually a large generating plant with a system of lines to get the electricity to the user. • A generator may be used in case of a power outage, when a loss of power may result in the loss of life, crops, etc.

14. OBJECTIVE 5 continued • A. A conductor is a material that allows electricity to easily pass along it or through it. • 1. Metals are good conductors because of the high concentration of free electrons they contain. • 2. Wires used for electrical work are frequently copper or aluminum because they are good conductors of electricity. • 3. Water is a conductor of electricity. Things that contain water (people, animals, trees, etc.) are also conductors.

15. OBJECTIVE 5 continued • B. An insulator is a material that prevents or reduces the passage of electricity. • 1. Insulators do not allow electrons to flow. • 2. Rubber, porcelain, and glass are all good electrical insulators. • 3. Electric wires are generally covered with a layer of plastic insulation. A conductor (wire) without insulation (plastic) is dangerous. • 4. Tools that are commonly used when working with electricity generally have a layer of plastic insulation on their handles to prevent a shock.

16. OBJECTIVE 2: Explain how electricity is produced. • Anticipated Problem: How is electricity produced? • II. Electric utility power stations use turbines, water wheels, or some other similar machine to generate electricity. Power stations must have a source of energy to run the machinery they use to generate electricity. Most of the electricity in the United States is produced in turbines driven by steam.

17. OBJECTIVE 2 continued • A. Coal can be burned in large furnaces to heat water to make steam that pushes the blades of a turbine. More than half (51%) of the electricity generated in the United States in 2009 used coal as its source of energy. • B. Nuclear power is used to create steam by heating water through a process called nuclear fission. Nuclear power generated 21% of the nation’s electricity in 2009. • C. Natural gas can be burned to heat water for steam, or it can be burned to produce gases that directly operate a turbine. Natural gas was used to generate 17% of our electricity in 2009.

18. OBJECTIVE 3 continued • A. Electricity leaves the power station and is sent over lines on tall towers. The very strong current from a power plant must travel long distances to get where it is needed. Current isthe flow of electricity through a cable. • B. Electricity loses some of its strength as it travels. It must be helped along by transformers, which boost or “step up” its power. A transformer is a device that transfers electrical energy from one circuit to another with a change in voltage, current, phase, or impedance.

19. Voltage • The pressure in a circuit that causes the electrons or current to flow. • It is sometimes referred to as electromotive force (EMF). • A volt is the unit by which electrical pressure is measured with a voltmeter.

20. Voltage • When electricity must be carried a long distance through wires, there will be a decrease in voltage, referred to as voltage drop. • Voltage drop occurs due to resistance in the conductors.

21. Amperage • The amount of electrical current flowing past a point in a circuit. • Amperage is measured with an ammeter.

22. OBJECTIVE 3 continued • C. Before electricity is usable to us, its voltage must be decreased. Voltageis the strength of the electricity. Different kinds of transformers are responsible for “stepping down” electricity’s power. • E. When the electricity reaches our homes, another transformer reduces the electricity down to just the right level to be used in our appliances, lights, and other household items.

23. OBJECTIVE 3 continued • When a circuit uses too much electricity, an overcurrent causes a circuit breaker to trip, shutting down the power to that circuit. • The service entrance is grounded with a wire connected to a ground rod driven several feet into the ground. • Service Panel • Follows the meter. • It houses the circuit breakers for the system and is used to distribute the power to individual circuits throughout the system.

24. Overcurrent • Another type of breaker is a GFCI (ground-fault circuit interrupter). • A GFCI is extremely sensitive to circuit imbalances in order to protect people who are using electrical devices near damp areas such as in bathrooms, kitchens, outside, etc.

25. Watts or wattage • Is a measure of electrical power. • Electrical power is work being done by current(amperage) under pressure(voltage) in getting the electrons through the resistance of wires and machines back to the generator. • Units of 1,000 watts are called kilowatts. • The relationship between watts(P), amps(I), and volts(E) is P=I x E.

26. OBJECTIVE 3 continued • F. A cable carries the electricity into the house through a meter that measures how much electricity is being used. • G. From the meter, electricity runs through a meter box throughout the walls into outlets in the home. The electricity is always waiting in the wires to be used when something is turned on. • H. Electricity travels at the speed of light (186,000 miles per second).

28. Next Class… • Don’t forget your supplies: • 2 AA batteries • Box • Picture

29. National Electrical Code (NEC) • Guidelines for electrical wiring have been established by the National Electrical Code (NEC) to ensure the safe use of electricity.

30. OBJECTIVE 4: Explain circuits, and describe the difference between an open circuit and closed circuit. • IV. Electricity travels in a circuit. A circuit is a route around which an electrical current can flow, beginning and ending at the same point. The word circuit comes from the word circle.

31. OBJECTIVE 4 continued • A. Circuits are formed by wires, appliances, and other devices. • B. A circuit requires at least two wires to handle the flow of the current. • 1. One wire (known as “hot”) carries the current from the source to where it is used. • 2. The other wire (neutral) carries the current back. • 3. Most electrical circuits also have a third wire called a ground wire. Ground wires prevent shock in case the other wires fail, a short occurs, or excess charge builds up. Ground wires are attached to metal rods driven into the ground several feet.

32. OBJECTIVE 4 continued • C. An open circuit is a circuit that has been disconnected by a switch or another open in the line. When you turn a light switch off, you are opening the circuit. • D. A closed circuit is a circuit that is continuously providing a complete path for the flow of electricity. When you turn a light switch on, you are closing, or completing, the circuit.

33. OBJECTIVE 6: Identify basic electrical safety tips. • What are some basic electrical safety tips?

34. OBJECTIVE 6 continued • A. Fix or replace loose-fitting plugs and missing or broken wall plates. These can overheat and cause a fire. • B. Use safety covers in all unused outlets to prevent children from sticking anything into the outlet. • C. Do not work with electricity in damp areas. Never handle electrical equipment with wet hands or while standing in a wet or damp place.

35. OBJECTIVE 6 continued • D. To help prevent electrocution, a ground fault circuit interrupter (GFCI) should be used in any area where water and electricity may come in contact. • E. Do not try to fix electrical devices that are not functioning properly. Let a professional fix them. • F. Extension cords and electrical appliance cords with cracks, frays, exposed wires, faulty plugs, poor insulation, and loose connections should be immediately replaced or fixed by a qualified person.

36. OBJECTIVE 6 continued • G. Never pull a plug from an outlet while the equipment is in operation. This creates an arc and will eventually foul the plug or the outlet, which can cause electrical shock or a possible fire. • H. Always unplug items by firmly grasping the plug itself. Never yank the cord. • I. Do not hang electrical cords on nails, staple them to walls or other objects, run them under carpet or rugs, rest furniture on them, or run them around pipes.

37. OBJECTIVE 6 continued • J. Do not use extension cords as permanent wiring installations. • K. Do not overload outlets or power strips. • L. Do not leave something plugged in when it is not in use, unless it is designed for continuous operation. • M. Never force a plug into an outlet if it doesn’t fit.

38. OBJECTIVE 6 continued • N. Never let anyone stick anything but a plug or a cover into an outlet. • O. Use the correct wattage of light bulb for the fixture. • P. Make sure light bulbs are screwed in securely. Loose bulbs may overheat. • Q. Never leave a plugged-in appliance where it might fall into water. If a plugged-in appliance does fall into the water, NEVER reach in to pull it out even if it is turned off.

39. REVIEW • 1. What is electricity? What are the different types of electricity? • 2. How is electricity produced? • 3. How does electricity travel? • 4. What is a circuit? What is the difference between an open circuit and a closed circuit? • 5. What is the difference between conductors and insulators? • 6. What are some basic electrical safety tips?