## Electricity and magnetism

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#### Study Guide Electricity and magnetism Science, Grade 4

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ELECTRICITY AND MAGNETISM Electricity Electricity is the flow of electrical charge. Atoms are made of three different particles, of which some have a positive charge, some have a negative charge, and some have no charge at all. Matter usually has the same number of positive and negative charges, making it neutral. Static Electricity is the imbalance of positive or negative charges between objects. If two objects have opposite charges, they’ll pull toward each other. Objects that have the same charge will repel each other. Lesson Checkpoint: What is static electricity? Electrical Circuits A simple circuit is a circuit where an electric charge flows in only one path. In a simple circuit that has two bulbs, if one of the bulbs burns out the other bulb will go out too. A parallel circuit has two or more paths the electric charge can flow through. © 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 a parallel circuit, if one bulb goes out, the other bulb will stay lit. Lesson Checkpoint: What is the difference between a simple and a parallel circuit? Two Main Types of Current AC = Alternating Current which is an electric current that reverses its direction at regular intervals. The outlets in our houses supply alternating current. The same amount of electrical charge flows through a circuit regardless of the direction of the current. DC = Direct Current, which is an electric current flowing in one direction only, but it may increase and decrease. DC is the kind of electricity made by a battery that has positive and negative terminals. Lesson Checkpoint: What are two types of current? Battery Cells A dry cell battery’s contents cannot be spilled. A wet cell battery is a battery whose contents can be spilled, like the batteries used in a car. Lesson Checkpoint: What is a wet cell battery? © 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.
Electricity Safety It is important to be very careful around any type of electricity. You should never touch wires, outlets, or any electrical device that you are not sure about. There are some tools and devices that have been created to make using electricity safer, like a fuse. A fuse is a safety device that has a metal wire which melts and stops the electrical current from flowing through the circuit when the current becomes too strong. A transformer allows electricity to be safely transmitted over long distances at a fast rate of speed. Electricity travels faster at high voltages. Electricity can be transmitted at high voltages because transformers change that voltage back into a lower voltage so that it is safe to use. Lesson Checkpoint: What is the purpose of a fuse? Magnetism Magnetism is the property of attracting certain kinds of metals. The invisible field around a magnet is called a magnetic field. © 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.
Magnets have two poles, a North end and a South end. Like poles repel each other while opposite poles attract, meaning the North pole on one magnet will attract the South pole on another magnet. The Earth is a Magnet? Earth acts as a large magnet, with its magnetic fields being strongest at its poles, which are not exactly at the North and South Pole. A compass is a tool that has a small needle that responds to the Earth’s magnetic field by always pointing North. Lesson Checkpoint: What is magnetism? Electromagnetism An electromagnet is a coil of wire through which an electric current passes. An electromagnet has a coil wrapped around an iron core. There are several ways you can make an electromagnet stronger. You can: increase the number of coils, increase the amount of current running through the wire, and increase the size of the core that the wire coils around to make the electromagnet stronger. Lesson Checkpoint: What is one way to strengthen an electromagnet? Using Electricity and Magnets Together A generator uses magnets and wires to turn mechanical energy into electrical energy by using the wind, falling water, and even steam. © 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.