* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download electromagnetic induction
Three-phase electric power wikipedia , lookup
Magnetochemistry wikipedia , lookup
Insulator (electricity) wikipedia , lookup
Earthing system wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Computational electromagnetics wikipedia , lookup
Electrical resistance and conductance wikipedia , lookup
Superconductivity wikipedia , lookup
Hall effect wikipedia , lookup
Wireless power transfer wikipedia , lookup
Multiferroics wikipedia , lookup
High voltage wikipedia , lookup
Force between magnets wikipedia , lookup
Electric current wikipedia , lookup
History of electric power transmission wikipedia , lookup
Superconducting magnet wikipedia , lookup
Scanning SQUID microscope wikipedia , lookup
Electromagnetic compatibility wikipedia , lookup
Lorentz force wikipedia , lookup
Faraday paradox wikipedia , lookup
Eddy current wikipedia , lookup
Electrical injury wikipedia , lookup
Electricity wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Electromotive force wikipedia , lookup
Electric machine wikipedia , lookup
History of electrochemistry wikipedia , lookup
Magnetic core wikipedia , lookup
History of electromagnetic theory wikipedia , lookup
Alternating current wikipedia , lookup
History of geomagnetism wikipedia , lookup
Magnetism Section 3 Section 3: Electric Currents from Magnetism Preview • Key Ideas • Bellringer • Electromagnetic Induction • The Electromagnetic Force • Transformers Magnetism Section 3 Key Ideas 〉What happens when a magnet is moved into or out of a coil of wire? 〉How are electricity and magnetism related? 〉What are the basic components of a transformer? Magnetism Section 3 Bellringer 1. List as many items as you can that use DC current. (Hint: Batteries supply DC current.) 2. List as many items as you can that use AC current. (Hint: Standard wall outlets supply AC current.) 3. If you want to plug a CD player that normally uses batteries into a wall socket, an AC adapter is required. What is the function of the AC adapter? 4. Electric power that goes into a neighborhood must be stepped down, or decreased, in voltage before it goes into a home. Explain why this is necessary. Magnetism Section 3 Electromagnetic Induction 〉What happens when a magnet is moved into or out of a coil of wire? 〉Moving a magnet into and out of a coil of wire causes charges in the wire to move. • electromagnetic induction: the process of creating a current in a circuit by changing a magnetic field • Faraday’s law states: An electric current can be produced in a circuit by a changing magnetic field crossing the circuit. Magnetism Section 3 Electromagnetic Induction, continued • As the loop moves in and out of the magnetic field of the magnet, a current is induced in the circuit. • Rotating the circuit or changing the strength of the magnetic field will also induce a current in the circuit. • Electromagnetic induction obeys conservation of energy. – Pushing a loop through a magnetic field requires work. Magnetism Section 3 Electromagnetic Induction, continued Magnetism Section 3 Visual Concept: Ways of Inducing a Current in a Circuit Click the button below to watch the Visual Concept. Magnetism Section 3 Electromagnetic Induction, continued • The magnetic force acts on moving electric charges. – The force is at its maximum value when the charge moves perpendicularly to the field. – As the angle between the charge’s direction and the direction of the magnetic field decreases, the force on the charge decreases. • The magnetic force acts on wires carrying a current. Magnetism Section 3 Electromagnetic Induction, continued Magnetism Section 3 Electromagnetic Induction, continued • Generators convert mechanical energy into electrical energy. • generator: a machine that converts mechanical energy to electrical energy • alternating current (AC): an electric current that changes direction at regular intervals – For each half rotation of the loop, the current produced by the generator reverses direction. • AC generators produce the electrical energy you use in your home. Magnetism AC Generator Section 3 Magnetism Induced Current Section 3 Magnetism Section 3 Visual Concept: Function of a Generator Click the button below to watch the Visual Concept. Magnetism Section 3 The Electromagnetic Force 〉How are electricity and magnetism related? 〉Electricity and magnetism are two aspects of a single force, the electromagnetic force. • The energy that results from these two forces is called electromagnetic (EM) energy. • Light is a form of electromagnetic energy. • EM waves are made up of oscillating electric and magnetic fields that are perpendicular to each other. Magnetism Section 3 Visual Concept: Electromagnetic Waves Click the button below to watch the Visual Concept. Magnetism Section 3 Transformers 〉 What are the basic components of a transformer? 〉In its simplest form, a transformer consists of two coils of wire wrapped around opposite sides of a closed iron loop. • transformer: a device that increases or decreases the voltage of alternating current • primary coil: wire attached to a source of alternating current • secondary circuit: wire attached to an appliance Magnetism Section 3 Transformers, continued • Current in the primary coil, creates a changing magnetic field that magnetizes the iron core. • The changing magnetic field of the iron core then induces a current in the secondary coil. • Transformers can increase or decrease voltage. – The voltage induced in the secondary coil of a transformer depends on the number of loops, or turns, in the coil. Magnetism Section 3 Transformers, continued • In a step-up transformer, the primary coil has fewer turns than the secondary coil does. – The voltage across the secondary coil is greater than the voltage across the primary coil. • In a step-down transformer, the secondary coil has fewer loops than the primary coil does. – The voltage across the secondary coil is lower than the voltage across the primary coil. Magnetism Section 3 Transformers, continued • Transformers must obey the law of conservation of energy. – The current in the secondary coil of a step-up transformer is always less than the current in the primary coil. • Transformers are used in the transfer of electrical energy. Magnetism Transformers, continued Section 3 Magnetism Section 3 Visual Concept: Transformer Click the button below to watch the Visual Concept.