Table of Contents

1. Table of Contents • Electric Charge and Static Electricity • Electric Current • Batteries • Electric Circuits • Electric Power • Electrical Safety

2. - Electric Charge and Static Electricity Electric Charge • Charges that are the same repel each other. Charges that are different attract each other.

3. - Electric Charge and Static Electricity Electric Force • An electric field is a region around a charged object where the object’s electric force is exerted on other charged objects.

4. - Electric Charge and Static Electricity Electric Force • An electric field is a region around a charged object where the object’s electric force is exerted on other charged objects.

5. - Electric Charge and Static Electricity Transferring Charge • There are three methods by which charges can be transferred to build up static electricity: charging by friction, by conduction, and by induction.

6. - Electric Charge and Static Electricity Transferring Charge • An electroscope can be used to detect the presence of a charge.

7. - Electric Charge and Static Electricity Previewing Visuals • Before you read, preview Figure 4. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions. Transferring Static Electricity Q. What are three ways that static electricity can be transferred? A. Charging by friction, charging by conduction, and charging by induction Q. Why does an object become charged? A. An object becomes charged when electrons are transferred from one location to another.

8. - Electric Charge and Static Electricity Links on Static Electricity • Click the SciLinks button for links on static electricity.

9. - Electric Charge and Static Electricity Lightning • Click the Video button to watch a movie about lightning.

10. End of Section:Electric Charge and Static Electricity

11. - Electric Current Flow of Electric Charges • Electric current is the continuous flow of electric charges through a material.

12. - Electric Current An Electric Circuit • An electric circuit is a complete, unbroken path through which electric charges can flow.

13. - Electric Current Resistance • Two factors that affect the resistance of water flowing in a pipe are diameter and length. The diameter and length of a wire also affect resistance in a circuit.

14. - Electric Current Outlining Electric Current • As you read, make an outline about electric current. Use the red headings for the main ideas and the blue headings for the supporting ideas. • Flow of Electric Charges • What Is Electric Current? • Current in a Circuit • Conductors and Insulators • Conductors • Insulators • Voltage • Charges Need Energy to Flow • Voltage • Voltage Sources • Resistance • Current Depends on Resistance • Factors That Determine Resistance • Path of Least Resistance

15. - Electric Current More on Electric Current • Click the PHSchool.com button for an activity aboutelectric current.

16. End of Section:Electric Current

17. - Batteries The First Battery • Volta built the first electric battery by layering zinc, paper soaked in salt water, and silver.

18. - Batteries Electrochemical Cells • An electrochemical cell is a device that transforms chemical energy into electrical energy.

19. - Batteries Electrochemical Cells • An electrochemical cell in which the electrolyte is a liquid is a wet cell.

20. - Batteries Electrochemical Cells • A dry cell is an electrochemical cell in which the electrolyte is a paste.

21. Examples: Key Terms: electrode terminal battery wet cell dry cell - Batteries Building Vocabulary • After you read the section, reread the paragraphs that contain definitions of Key Terms. Use the information you have learned to write a definition of each Key Term in your own words. Examples: Key Terms: chemical energy Chemical energy is the energy that chemical compounds store within the compounds. A metal in an electrochemical cell that is covered with electrolyte is called an electrode. The electrode part that sticks up above the electrolyte is called the terminal. chemical reaction A chemical reaction is a process in which substances change into other substances with different properties than the original substances. A battery is a series of electrochemical cells. electrochemical cell An electrochemical cell is an electrical device that changes chemical energy into electrical energy. A wet cell is an electrochemical cell that has liquid as its electrolyte. electrolyte An electrolyte is a substance in an electrochemical cell through which current flows. A dry cell is an electrochemical cell that has paste as its electrolyte.

22. End of Section:Batteries

23. When calculating voltage, you often use decimals. When you multiply two decimals, the number of decimal places in the product is the sum of the number of decimal places in each decimal you multiply. If a circuit has a resistance of 30.5 ohms and a current of 0.05 amps, what is its voltage? - Electric Circuits Decimals

24. Practice Problem Use Ohm’s law to calculate the voltage of a circuit with a resistance of 15.2 ohms and a current of 0.10 amps. 1.52 volts - Electric Circuits Decimals

25. The brake light on an automobile is connected to a 12-volt battery. If the resulting current is 0.40 amps, what is the resistance of the brake light? Read and Understand What information are you given? Battery Voltage = 12 V Current = 0.40 A - Electric Circuits Calculating Resistance

26. The brake light on an automobile is connected to a 12 volt battery. If the resulting current is 0.40 amps, what is the resistance of the break light? Plan and Solve What quantity are you trying to calculate? The resistance of the brake light What formula contains the given quantities and the unknown quantity? Resistance = Voltage/Current Perform the calculation. Resistance = 12 V/0.40 A = 30 Ω - Electric Circuits Calculating Resistance

27. The brake light on an automobile is connected to a 12-volt battery. If the resulting current is 0.40 amps, what is the resistance of the brake light? Look Back and Check Does your answer make sense? The answer makes sense because you are dividing the voltage by a decimal. The answer should be greater than either number in the fraction, which it is. - Electric Circuits Calculating Resistance

28. Practice Problem In a circuit, there is a 0.5-A current in the bulb. The voltage across the bulb is 4.0 V. What is the bulb’s resistance? 8.0 Ω (4.0 V ÷ 0.5 A) - Electric Circuits Calculating Resistance

29. Practice Problem A waffle iron has a 12-A current. If the resistance of the coils is 10 Ω, what must the voltage be? 120 V (12 A X 10 Ω) - Electric Circuits Calculating Resistance

30. - Electric Circuits Features of a Circuit • Simple symbols are used to diagram a circuit.

31. - Electric Circuits Series Circuits • In a series circuit, there is only one path for the current to take.

32. - Electric Circuits Parallel Circuits • In a parallel circuit, there are several paths for the current to take.

33. - Electric Circuits Series and Parallel Circuits Activity • Click the Active Art button to open a browser window and access Active Art about series and parallel circuits.

34. - Electric Circuits Comparing and Contrasting • As you read, compare and contrast series circuits and parallel circuits in a Venn diagram like the one below. Write the similarities in the space where the circles overlap and the differences on the left and right sides. Series Circuit Parallel Circuit Only one path for current to take Unbroken path that has a current Several paths for current to take

35. End of Section:Electric Circuits

36. - Electric Power Electric Power • The rate at which energy is transformed from one form to another is known as power. Power is measured in watts (W).

37. A household light bulb has about 0.5 amps of current in it. Since the standard household voltage is 120 volts, what is the power rating for this bulb? Read and Understand What information have you been given? Current = 0.5 A Voltage = 120 V - Electric Power Calculating Power

38. A household light bulb has about 0.5 amps of current in it. Since the standard household voltage is 120 volts, what is the power rating for this bulb? Plan and Solve What quantity are you trying to calculate? The power of the light bulb = ? What formula contains the given quantities and the unknown quantity? Power = Voltage X Current Perform the calculation. Power = 120 V X 0.5 A Power = 60 W - Electric Power Calculating Power

39. A household light bulb has about 0.5 amps of current in it. Since the standard household voltage is 120 volts, what is the power rating for this bulb? Look Back and Check Does your answer make sense? The answer is reasonable, because 60 W is a common rating for household light bulbs. - Electric Power Calculating Power

40. Practice Problem A flashlight bulb uses two 1.5-V batteries in series to create a current of 0.5 A. What is the power rating of the bulb? 1.5 W (3.0 V X 0.5 A) - Electric Power Calculating Power

41. Practice Problem A hair dryer has a power rating of 1,200 W and uses a standard voltage of 120 V. What is the current through the hair dryer? 10 A (1,200 W ÷ 120 V) - Electric Power Calculating Power

42. - Electric Power Asking Questions • Before you read, preview the red headings. In a graphic organizer like the one below, ask a what or how question for each heading. As you read, write answers to your questions. Question Answer What is electric power? Electric power is the rate at which electrical energy is transformed into another form of energy.

43. - Electric Power Links on Electric Power • Click the SciLinks button for links on electric power.

44. End of Section:Electric Power

45. - Electrical Safety Electrical Equipment and Fires • If electrical equipment is not properly used and maintained, it can cause fires. The circle graph shows the percentage of fires caused by different types of electrical equipment.

46. The percentage of fires caused by a certain type of electrical equipment Reading Graphs: What determines the size of each wedge in the graph? - Electrical Safety Electrical Equipment and Fires

47. 15% Reading Graphs: What percentage of fires are caused by appliances? - Electrical Safety Electrical Equipment and Fires

48. Cooking equipment is responsible for the most fires. Heating and cooling equipment is responsible for the fewest fires. Interpreting Data: Which category of equipment is responsible for the most fires? Which category is responsible for the fewest fires? - Electrical Safety Electrical Equipment and Fires

49. - Electrical Safety Grounding • One way to protect people from electric shock and other electrical danger is to provide an alternate path for electric current.

50. - Electrical Safety Breaking a Circuit • In order to prevent circuits from overheating, devices called fuses and circuit breakers are added to circuits.