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What Should I Be Doing?? Open notebook to page 114 and write/draw everything you can think of about magnets, magnetic field, electricity, electric field, and electromagnets. Magnetic, Electric, and Gravitational Fields Forces between objects act when they are in direct contact and when they are not touching. Magnetic, electric, and gravitational fields act at a distance. What is a field? • A field is a region of influence surrounding an object. – Example: Baseball field, battlefield, football field, etc. • A field model can be used to explain how 2 objects are exerting (applying) forces on each other without touching. • When a second object is placed in this region, the field exerts a force on the object and can cause the object to change motion. • 3 types of fields – Electric, Magnetic, and Gravitational Electric Field • Definition: A region where charged objects exert forces on other charged objects. • Examples: Light bulbs, cell phones, batteries, TV, etc. • Properties: Charged/Uncharged Particles – Protons – Positive charge – Electrons – Negative charge – Neutrons – No charge Electric Field • The force between electric charges can be attractive or repulsive. – Opposite charges attract each other – Similar charges repel each other • Electric force increases as electric charges increase. • Electric force decreases (weakens) with increasing distance. Electrical Energy • Benefits Us: The electricity that we use is transformed from mechanical energy to electrical energy in power plants. • Other examples of electrical energy transformations: – Batteries or cells: Convert chemical energy into electrical energy – Solar cell: Convert solar energy to electrical energy – Generator: Converts kinetic energy into electrical energy – Motor: Converts electrical energy into kinetic energy Magnetic Field • The Science Behind Magnets: How Do They Work: – https://www.youtube.com/watch?v=MZtTVsIOA9c (5 minutes) Magnetic Field • Definition: Region where a magnet, electric current, or a moving charged particle in which a magnetic force exerts force on another magnet, electric current, or charged particles. Magnetic Field Lines • To help us see the magnetic field lines, we use iron fillings to see the lines. – Example: Magnetic Potential Energy Lab • Since magnetics are attracted to iron, we are able to see the field lines. Examples of Magnetic Field • • • • • • • Magnets TV Cell Phones Solar Wind Auroras Compass Mid-Ocean ridges Earth’s Magnetic Field • Earth has a magnetic field due to the composition of the core (iron and nickel). • The Earth’s Magnetic Field is response for deflecting solar wind, which are charged particles that come from the Sun. Auroras • Solar wind energizes the magnetosphere, which causes the acceleration of elections there – The charged particles then interact with oxygen and nitrogen in the upper atmosphere causing them to emit light. – The color depends on the type of atom that is excited and how excited it becomes, How Does a Compass Work? • The North end of a compass needle (a magnet) points to the geographic North pole. • The geographic North pole is the magnetic South pole. – Opposites attract! Evidence of Earth’s Magnetic Field • Remember learning about this? – Rocks on either side of the mid ocean ridge – Iron in molten rock lines up in the direction of Earth’s magnetic field – when it cools into rocks, it leaves a record of Earth’s magnetic field strength and field direction. Properties: Magnetic Field • Magnets have 2 distinct, opposite ends. – North pole and South pole. – Field lines start from N to S. • 2 types of magnets – Permanent magnet – Electromagnet Magnetic Field • Attractive/Repulsive – Opposite poles are attracted to each other. – Similar poles are repel each other. • Increase / Decrease – Magnetic force increases with decreasing distance. – Magnetic force decreases (weakens) rapidly with increasing distance. • Benefits Us: – Earth’s magnetic field protects us from solar wind – Directions – Compass Electric and Magnetic Fields are Related! (On back side of notes) • Magnetic fields can produce electrical currents in conductors (copper). • Electromagnets are temporary magnets that lose their magnetism when the electric current is turned off. Electromagnets • In 1820, Danish physicist Hans Christian Oersted discovered that when an electric current was in a wire, the compass needle rotated. • If the compass needle rotated, it must have been because of a magnetic field. • An electric current flowing through a wire forms a magnetic field! • He also created aluminum for the first time! (He was also good friends with Hans Christian Andersen, who was the original author of “The Ugly Duckling” and “The Little Mermaid.”) Electromagnets • An electromagnet is a magnet that runs on electricity. • An electromagnet works as the electric current passes through the wire, small magnetic regions align with the wire’s magnetic field. • The strength of the electromagnet can be increased or decreased by changing the electric current passing through the wires. Electromagnets • If the wire is twisted into a loop (coil), the magnetic field is increased. • The coil of wire spinning around a magnet can form an electric current. • Examples: Motors, generators, blenders, speakers, washing machine, and electric toothbrushes. – https://www.youtube.com/watch ?v=rgg1WUJhUc4 (1 minute) Simple Electric Motors • Electric motors turn electrical energy into mechanical energy. – It contains an electromagnet that rotates between the poles of a magnet. – The coil of the electromagnet is connected to a battery or other source of electric current. – When an electric current flows through the wire in the electromagnet, a magnetic field is produced in the coil. Simple Electric Motors • The coil rotates because like poles repel and opposite poles attract. • The rotating coil can be attached to a shaft and a blade in an electric fan. Generators • Generators work the opposite way. (Turn mechanical energy is changed to electric energy.) – A coil of wire is wrapped around an iron core. – The wire is placed inside a magnetic field, and the magnets are turned using a turbine. • Turbines are huge wheels that rotate when pushed by water, wind, or steam. Generators • Generators at Power Plants produce electric energy for our homes. • Watch: https://www.youtube.com/watch?v=d_aTC0iKO68 History: New Deal and TVA • https://www.youtube.com/watch?v=URqvgTUekQQ (5 minutes) • 1930s: The dams controlled floods, improved navigation and generated electricity. • The most dramatic change in Valley life came from the electricity generated by TVA dams. • Electric lights and modern appliances made life easier and farms more productive. • Electricity also drew industries into the region, providing desperately needed jobs. Wheeler Dam – Village, Alabama Huffman Dam – Dayton, Ohio Gravitational Fields • Definition: The region of space surrounding a body in which another body experiences a force of gravitational attraction. • Examples: Gravity acting on Earth and pulling objects toward the ground Properties of Gravitational Field • Weight vs. Mass – Weight is a gravitational force that is often confused with mass. – Mass is the amount of matter a body contains – Weight is proportional to mass, but depends on the gravitational field at a particular location. – Object on Earth will weigh more than the same object on the moon. Mass vs. Weight Video • https://www.youtube.com/watch?v=gjfLI 7aJKmQ Gravitational Field • Attractive/Repulsive – Gravity is an attractive force since it pulls objects toward each other. • Force Increases & Decreases – The gravitational force increases with the mass of the objects. – The gravitational force decreases (weakens) with increasing distance. Benefits Us? • Keeps us on the ground instead of floating everywhere! Toys in Space • Introduction: – https://www.youtube.com/watch?v=khLdL3X5acY&list=PLi uUQ9asub3Ru9GIOTbZFRa4f2R_kM0tx&index=1 • YoYo: – https://www.youtube.com/watch?v=ZzSt8t7jsdo&list=PLiuU Q9asub3Ru9GIOTbZFRa4f2R_kM0tx&index=3 • Jump Rope: – https://www.youtube.com/watch?v=Kmvj6f3TPo&index=4&list=PLiuUQ9asub3Ru9GIOTbZFRa4f2R_ kM0tx • Soccer: – https://www.youtube.com/watch?v=Ayhuejk88CE&index=1 2&list=PLiuUQ9asub3Ru9GIOTbZFRa4f2R_kM0tx • Climbing Bear: – https://www.youtube.com/watch?v=hZSUUHiOeIo&index=1 0&list=PLiuUQ9asub3Ru9GIOTbZFRa4f2R_kM0tx Acting At A Distance (Write this underneath your notes on the lined paper) – Magnetic Field: • When magnets are not touching you still feel tension or attraction between them. – Electric Field: • When 2 electrically charged objects meet, they oppose each other. – Gravitational Field: • When an object falls, gravity is pulling it down without directly touching the object. Name that field!