Magnetism, Electricity & Electromagnetism

1. Magnetism, Electricity & Electromagnetism Ms. Mannix 2016 Honors Physical Science DFA

2. - What Is Magnetism? Magnetic Fields • Magnetic field lines spread out from one pole, curve around the magnet, and return to the other pole.

3. - What Is Magnetism? Magnetic Fields • When the magnetic fields of two or more magnets overlap, the result is a combined field.

4. - What Is Magnetism? Magnetic Field Lines Activity • Click the Active Art button to open a browser window and access Active Art about magnetic field lines.

5. - Inside a Magnet The Atom • An atom contains neutrons and positively charged protons in its nucleus. Negatively charged electrons move randomly throughout an atom.

6. - Inside a Magnet Magnetic Domains • In a magnetized material, all or most of the magnet domains are arranged in the same direction.

7. - Inside a Magnet Magnetic Domains • Modern magnets come in a variety of shapes and are made from many different materials.

8. - Inside a Magnet Making and Changing Magnets • Each piece of a magnet retains its magnetic properties after it is cut in half.

9. - Magnetic Earth Earth as a Magnet • Just like a bar magnet, Earth has a magnetic field surrounding it and two magnetic poles.

10. - Magnetic Earth Movement of Earth’s Magnetic Poles • Earth’s magnetic poles move slowly over time. The data in the table show the position of Earth’s magnetic north pole in specific years.

11. The average speed of the pole’s movement is increasing. Interpreting Data: What is the trend in the speed of the pole’s movement? - Magnetic Earth Movement of Earth’s Magnetic Poles

12. Between 1948 and 2001, the pole has moved 857 km (150 km + 120 km +120 km + 180 km + 287 km). Calculating: What is the total distance the pole has traveled over the time shown? - Magnetic Earth Movement of Earth’s Magnetic Poles

13. The average speed increased by 23 km/yr from 1994 to 2001. That is an increase of 3.3 km/yr per year. There are 9 years between 2001 and 2010. Therefore, a good prediction is that the average speed in 2010 will be 29.7 km/yr. Predicting: Using the data, predict the average speed of the pole’s movement between 2001 and 2010. Explain. - Magnetic Earth Movement of Earth’s Magnetic Poles

14. - Magnetic Earth The Magnetosphere • The solar wind causes Earth’s magnetic field to stretch out on the side of Earth not facing the sun.

15. Electricity

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

17. - 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.

18. - 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.

19. - 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.

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

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

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

23. - 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.

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

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

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

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

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

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

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

31. 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

32. 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

33. 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

34. 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

35. 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

36. 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

37. 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

38. - 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).

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? Read and Understand What information have you been given? Current = 0.5 A Voltage = 120 V - Electric Power Calculating Power

40. 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

41. 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

42. 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

43. 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

44. Calculating Electrical Energy • E=Pt

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.