 # Electricity Magnetism Electricity Electromagnetism Ms Mannix 2016 Honors

• Slides: 66 Electricity Magnetism, Electricity & Electromagnetism Ms. Mannix 2016 Honors Physical Science DFA Electricity - What Is Magnetism? Magnetic Fields Magnetic field lines spread out from one pole, curve around the magnet, and return to the other pole. Electricity - What Is Magnetism? Magnetic Fields When the magnetic fields of two or more magnets overlap, the result is a combined field. Electricity - 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. Electricity - Inside a Magnet The Atom An atom contains neutrons and positively charged protons in its nucleus. Negatively charged electrons move randomly throughout an atom. Electricity - Inside a Magnetic Domains In a magnetized material, all or most of the magnet domains are arranged in the same direction. Electricity - Inside a Magnetic Domains Modern magnets come in a variety of shapes and are made from many different materials. Electricity - Inside a Magnet Making and Changing Magnets Each piece of a magnet retains its magnetic properties after it is cut in half. Electricity - Magnetic Earth as a Magnet Just like a bar magnet, Earth has a magnetic field surrounding it and two magnetic poles. Electricity - 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. Electricity - Magnetic Earth Movement of Earth’s Magnetic Poles Interpreting Data: What is the trend in the speed of the pole’s movement? The average speed of the pole’s movement is increasing. Electricity - Magnetic Earth Movement of Earth’s Magnetic Poles Calculating: What is the total distance the pole has traveled over the time shown? Between 1948 and 2001, the pole has moved 857 km (150 km + 120 km + 180 km + 287 km). Electricity - Magnetic Earth Movement of Earth’s Magnetic Poles Predicting: Using the data, predict the average speed of the pole’s movement between 2001 and 2010. Explain. 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. Electricity - Magnetic Earth The Magnetosphere The solar wind causes Earth’s magnetic field to stretch out on the side of Earth not facing the sun. Electricity Electricity - Electric Charge and Static Electricity Electric Charges that are the same repel each other. Charges that are different attract each other. Electricity - 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. Electricity - 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. Electricity - 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. Electricity - Electric Charge and Static Electricity Transferring Charge An electroscope can be used to detect the presence of a charge. Electricity - Electric Current Flow of Electric Charges Electric current is the continuous flow of electric charges through a material. Electricity - Electric Current An Electric Circuit An electric circuit is a complete, unbroken path through which electric charges can flow. Electricity - 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. Electricity - Batteries The First Battery Volta built the first electric battery by layering zinc, paper soaked in salt water, and silver. Electricity - Batteries Electrochemical Cells An electrochemical cell is a device that transforms chemical energy into electrical energy. Electricity - Batteries Electrochemical Cells An electrochemical cell in which the electrolyte is a liquid is a wet cell. Electricity - Batteries Electrochemical Cells A dry cell is an electrochemical cell in which the electrolyte is a paste. Electricity - Electric Circuits Features of a Circuit Simple symbols are used to diagram a circuit. Electricity - Electric Circuits Series Circuits In a series circuit, there is only one path for the current to take. Electricity - Electric Circuits Parallel Circuits In a parallel circuit, there are several paths for the current to take. Electricity - Electric Circuits Decimals 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? Electricity - Electric Circuits Decimals 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 Electricity - Electric Circuits Calculating Resistance 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 Electricity - Electric Circuits Calculating Resistance 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 Electricity - Electric Circuits Calculating Resistance 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. Electricity - Electric Circuits Calculating Resistance 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) Electricity - Electric Circuits Calculating Resistance 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) Electricity - Electric Power The rate at which energy is transformed from one form to another is known as power. Power is measured in watts (W). Electricity - Electric Power Calculating Power 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 Electricity - Electric Power Calculating Power 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 Electricity - Electric Power Calculating Power 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. Electricity - Electric Power Calculating Power 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) Electricity - Electric Power Calculating Power 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) Electricity Calculating Electrical Energy E=Pt Electricity - 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. Electricity - Electrical Safety Electrical Equipment and Fires Reading Graphs: What determines the size of each wedge in the graph? The percentage of fires caused by a certain type of electrical equipment Electricity - Electrical Safety Electrical Equipment and Fires Reading Graphs: What percentage of fires are caused by appliances? 15% Electricity - Electrical Safety Electrical Equipment and Fires Interpreting Data: Which category of equipment is responsible for the most fires? Which category is responsible for the fewest fires? Cooking equipment is responsible for the most fires. Heating and cooling equipment is responsible for the fewest fires. Electricity - Electrical Safety Grounding One way to protect people from electric shock and other electrical danger is to provide an alternate path for electric current. Electricity - Electrical Safety Breaking a Circuit In order to prevent circuits from overheating, devices called fuses and circuit breakers are added to circuits. Electricity Graphic Organizer Devices to prevent circuits from overheating include Fuses Circuit breakers work by Melting Bending away from wires Electricity - What Is Electromagnetism? Electric Current and Magnetism An electric current produces a magnetic field. Electricity - What Is Electromagnetism? Solenoids The magnetic field produced by a current has three distinct characteristics. The field can be turned on or off, have its direction reversed, or have its strength changed. A solenoid is a type of electromagnet when the purpose is to generate a controlled magnetic field. Electricity - What Is Electromagnetism? Solenoids The magnetic field around a solenoid resembles that of a bar magnet. Electricity - What Is Electromagnetism? Electromagnets A doorbell rings as the magnetic field of an electromagnet turns on and off. Electricity - What Is Electromagnetism? Electromagnets are used to lift heavy objects. A switch is turned on in the crane so that a current is produced in the electromagnet. Electricity, Magnetism, and Motion Electrical Energy and Motion When a wire with current is placed in a magnetic field, electrical energy is transformed into mechanical energy. Electricity, Magnetism, and Motion Galvanometers An electric current is used to turn the pointer of a galvanometer. Electricity, Magnetism, and Motion Electric Motors An electric motor transforms electrical energy into mechanical energy. Electricity - Electricity From Magnetism Induction of Electric Current An electric current is induced in a conductor when the conductor moves through a magnetic field. Electricity - Electricity From Magnetism Induction of Electric Current If a magnet moves through a coil of wire, a current is induced in the wire. Electricity - Electricity From Magnetism Generators A generator uses motion in a magnetic field to produce an electric current. Electricity - Electricity From Magnetism Generators In most generators, a source of mechanical energy turns huge turbines such as this one. The turbine is attached to the armature of a generator, which produces current. Electricity Compare and Contrast http: //study. com/academy/lesson/electric-motors-generatorsconverting-between-electrical-and-chemical-energy. html Electricity - Electricity From Magnetism Transformers A transformer is a device that increases or decreases voltage. Electricity - Electricity From Magnetism Types of Transformers Voltage can be changed depending on the number of loops in the primary and secondary coils.