Transcript Unit F
Unit F Energy and Motion Chapter 15 Electricity and Magnetism Lesson 1: What is Static Electricity? Electric Charges 1. Many of the atoms that make up matter carry tiny units of electricity called electric charges. 2. There are two kinds of charges: positive and negative charges. a. Like charges repel or push away each other b. Unlike charges attract or pull toward each other c. Negative charges can move more easily from one material to another. Buildup and Discharge 1. Static Electricity is the buildup of electric charges on the surface of an object. 2. Electric Discharge is the loss or release of the built-up negative charges. a. A bolt of lightning is an example of electric discharge. Lesson 2: What is Electric Current? How Charges Move 1. In order for electric charges to be useful, they have to flow. 2. An Electric Current is the continuous flow of electric charges. Conductors and Insulators 1. Conductors are materials that allow electricity to pass through them easily. a. Examples: Metals (copper, aluminum, gold, and silver) and water 2. Insulators are materials that DO NOT allow electricity to pass through them easily. a. Examples: plastic, rubber, glass, air, and wood. Circuits and Switches 1. An Electric Circuit is the pathway that electric current follows. 2. Two kinds of Circuits a. Closed Circuits are circuits that are complete (No breaks in the path). b. Open Circuits are circuits that are incomplete (A break in the path). 3. A Switch is a device that opens or closes a circuit. a. When the switch is off the circuit is open (the light is off). b. When the switch is on the circuit is closed (the light is on) Two Types of Circuits 1. A Series Circuit is a circuit in which the parts are connected so that the electric current passes through a single path. 2. A Parallel Circuit is a circuit in which the parts are connected so that the electric current passes through more than one path. a. If you remove one part from the circuit, current can still flow. Electricity in the Home 1. The electric wiring in a house is connected in a parallel circuits. 2. If too much current passes through a circuit, the wires can overheat. 3. A fuse is a device that opens a circuit by melting or breaking. 4. A circuit breaker is a switch that opens when it overheats. 5. An electric cell (battery) is a device that changes chemical energy into electrical energy. Lesson 3: What Is a Magnet? Properties of Magnets 1. A Magnet is an object that attracts certain metals, mainly iron. 2. Magnetism is the magnet’s ability to attract materials. 3. Two types of magnets a. Permanent Magnets keep their magnetism for a long time. b. Temporary Magnets do not keep their magnetism for a long time. Magnetic Fields 1. The Magnetic Field is the space in which the force of a magnet can act. a. The force of the magnet is greatest at the magnetic poles (ends of the magnet) - Unlike poles attract to each other. - Like poles repel each other. Earth As a Magnet 1. The Earth acts like a magnet because the Earth’s center is made mostly of molten iron that produces a magnetic field as the Earth spins. 2. Two types of poles a. Geographic Poles are the ends of the imaginary line around which the earth rotates. b. Magnetic Poles are the ends of the earth where a compass needle will point. Lesson 4: How Do Electromagnets Work? Electricity and Magnetism Electromagnets 1. An Electromagnet is a strong temporary magnet that uses electricity to produce magnetism. a. The electromagnet is created when an electric current passes through a wire coiled around an iron core. b. Electromagnets are temporary because they can be turned off and on. c. Blenders, computer disk drives, and doorbells all have electromagnets. Motors and Generators 1. A Motor is a device that changes electrical energy into energy of motion. 2. A Generator is a device that uses magnetism to convert energy of motion into electrical energy.