* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Unit 9: Energy, electricity and magnetism
Magnetoreception wikipedia , lookup
Hall effect wikipedia , lookup
Faraday paradox wikipedia , lookup
Nanofluidic circuitry wikipedia , lookup
Electronic engineering wikipedia , lookup
Electric charge wikipedia , lookup
Alternating current wikipedia , lookup
Earthing system wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Electromotive force wikipedia , lookup
Electrical resistivity and conductivity wikipedia , lookup
Magnetochemistry wikipedia , lookup
Electromagnetic compatibility wikipedia , lookup
National Electrical Code wikipedia , lookup
Superconductivity wikipedia , lookup
Magnetic core wikipedia , lookup
Ground (electricity) wikipedia , lookup
Electromagnetism wikipedia , lookup
Electrification wikipedia , lookup
Scanning SQUID microscope wikipedia , lookup
Insulator (electricity) wikipedia , lookup
Electric current wikipedia , lookup
High voltage wikipedia , lookup
Electrical resistance and conductance wikipedia , lookup
Electrostatics wikipedia , lookup
Electrical engineering wikipedia , lookup
Electrical wiring wikipedia , lookup
Electric machine wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Force between magnets wikipedia , lookup
Electricity wikipedia , lookup
Electrician wikipedia , lookup
Static electricity wikipedia , lookup
Magnetotellurics wikipedia , lookup
History of geomagnetism wikipedia , lookup
Eddy current wikipedia , lookup
Unit 9: Energy, electricity and magnetism Natural science Electricity ● Electrical charges ● Electrical currents ● Electrical energy Electrical charges and static electricity Materials can receive electrical charges. A charge that objects receive under certain conditions is static electricity: ● Combing your hair with a plastic comb ● Rubbing a glass or plastic object with a wool cloth ● Rub a balloon against your hair These objects become positively or negatively electrically charged. ● Opposite charges (positive and negative) attract each other. ● Same charges (positive and positive / negative and negative) repel each other. Electrical currents are the transfer Electrical energy is associated with of an electrical charge through objects. This only works when the objects have opposite electrical charges. For example: electrical currents. Many of the machines we use need electrical energy. Storm clouds and Earth’s surface have opposite electrical charges, so electrical currents can jump from one to the other through the air. ● lightening Each end of a battery has an opposite electrical charge. When they are connected with a metal cable the charge moves from one pole to the other. Can produce changes in matter and can be transformed into other types of energy. ● Light bulbs are transferred into luminous energy ● Irons are transferred into thermal energy ● Motors are transferred into kinetic energy Conductive materials Materials and electrical currents Electrical currents are produced when a charge is moving from one object to another, along a material that allows it to move. Electrical conductors are things that allow currents to pass through them. Metals are good conductors ● copper Some non-metallic materials are also good conductors ● Graphite and salt water Insulating materials Electrical insulators are things that do not allow currents to pass through them. ● Wood, plastic and rubber Electrical circuits are groups of elements that allow electrical currents to flow. Components: Generators transform transform different energy into electrical energy and produce currents. ● Batteries transform chemical reactions into electrical energy ● Alternators, like windmills and hydraulic turbines, transform mechanical energy into electrical. ● Solar panels transform luminous energy into electrical using sunlight Conducting cables transport currents from the generator to the receptor. Usually insulated to avoid accidents and loss of current. Switches are used to tu1rn currents on and off by stopping and allowing it to pass. Receptors use the electrical energy that has been transported to them. ● Light bulbs - electrical into light ● Ovens - electrical into heat ● Electric motors - electrical into movement Magnetism Magnetism is the property allowing them to attract or repel other objects. Magnets are objects that have metal in their composition and are able to attract other objects that contain metal. Magnets and their characteristics All magnets have a magnetic field and two opposite poles, which attract, and two like poles, which repel. Magnetite is a naturally occurring mineral with magnetic properties. Magnets can also be produced artificially from some metals (iron, cobalt, nickel and neodymium). Poles: two areas usually at opposite end of the magnet, called north and south. Magnets with one pole do not exist and if you cut a magnet in half each half becomes a new magnet with two poles. Magnetic fields: the influence magnets have on space around them. The closer a magnet gets to a metallic objects the more intensely it starts to attract the object. Earth’s magnetism Earth’s center is a mixture of metals: mainly iron and nickel, which have magnetic properties. This makes Earth like a giant magnet, having a magnetic north and south pole which create a magnetic field. Earth’s magnetic poles do not coincide with geographical poles. Uses of magnetism: Compasses contain a small magnetic needle which detects Earth’s magnetic field and allows us to find direction. Electrical equipment contain materials with magnetic properties which allow us to store data. ● Credit cards, computers, and hard drives Many other appliances use magnets to keep them closed, hold things in place or are used in toys. ● Locks, bags, fridges, suitcases Magnets are also found with electricity in generators, electrical motors, speakers and microphones. Electromagnetism Is the use of electricity and magnetism, they are related. Electrical currents can generate a magnetic field and magnets can generate an electrical current. Electromagnets If we wrap a conducting wire around an iron bar and pass an electrical current through it, the iron bar will attract metal objects and turn into an electromagnet. If we switch off the current, the magnetic properties also stop. Electromagnets are temporary magnets. Uses: doorbells, some car brakes and clutches, machines that separate metallic residue in recycling plants Electromagnetic generators Are alternators. They use magnetism to generate electricity. If we put a magnet near a coiled conducting wire, the electromagnetic field of the magnet will generate a current in the wire, which is stronger if the magnet is more powerful. Ammeters are machines that measure electrical current. Uses: Power stations. Kinetic energy of water, wind or water vapour is used to move magnets that generates electricity.