Electromagnetism

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Study Guide Electromagnetism Science, Grade 6

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ELECTROMAGNETISM Overview The production of a magnetic field around an electrical current is called electromagnetism. This is shown in the diagram below. LESSON CHECKPOINT: What is electromagnetism? The fact that electricity alone produces magnetism is used in electromagnets to turn on and turn off strong magnetic fields. The diagram below shows an electromagnet being used to ring a doorbell. The magnetic field produced here when the circuit is closed is a combination of the magnetic force from the electrical current and the metal bar. Opening the circuit reduces the strength of the magnetic field and stops the clapper from striking the bell. © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
In junkyards, large electromagnets held by cranes are used to lift heavy loads of metal. When current is flowing the metal is lifted and when current stops flowing, the metal drops off the magnet. Magnets and Motion The placement of an electric current in a preexisting magnetic field can cause motion. When this happens, electrical energy is transformed into mechanical energy. The use of electrical energy to produce mechanical energy is the principle behind the workings of an electric motor. In a motor, the polarity of an electromagnet is continuously reversed within an existing magnetic field. The result of this is a continuous rotation of the electromagnet which in turn is connected to some type of shaft in an appliance like an electric drill. LESSON CHECKPOINT: How does an electric motor work? Induction A generator works in an opposite manner from a motor. By moving a conductor through a magnetic field, induced electricity is produced by induction. In this activity, mechanical energy is converted to electrical energy. In the diagram below, we see induction occurring in two different ways: © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.
Generators produce almost all of our electricity. By burning coal, oil or natural gas, large amounts of water are converted to steam which provides the mechanical energy needed to turn the generators. In some cases, falling water alone is enough to do this job. LESSON CHECKPOINT: How does a generator work? Managing Electric Flow Transformers are used to either increase or decrease voltage. Those that increase the voltage are called step up transformers and those that reduce the voltage are called step down transformers. Without transformers, getting electricity from power plants to our homes would be impossible. Coming out of large generators, voltages first have to be increased to be carried over long distances. When it nears our homes, these high voltages have to be reduced to safely enter and then work our appliances. LESSON CHECKPOINT: What are the two types of transformers and what does each type do? © Copyright NewPath Learning. All Rights Reserved. Permission is granted for the purchaser to print copies for non-commercial educational purposes only. Visit us at www.NewPathLearning.com.