* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Magnetism - faithphysics
Skin effect wikipedia , lookup
Van Allen radiation belt wikipedia , lookup
Magnetosphere of Jupiter wikipedia , lookup
Electromotive force wikipedia , lookup
Maxwell's equations wikipedia , lookup
Geomagnetic storm wikipedia , lookup
Magnetosphere of Saturn wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Edward Sabine wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Magnetic field wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Magnetometer wikipedia , lookup
Magnetic nanoparticles wikipedia , lookup
Electromagnetism wikipedia , lookup
Magnetic monopole wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Lorentz force wikipedia , lookup
Electromagnetic field wikipedia , lookup
Superconducting magnet wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetotellurics wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Magnetoreception wikipedia , lookup
Electromagnet wikipedia , lookup
Magnetochemistry wikipedia , lookup
Force between magnets wikipedia , lookup
Magnetism Chapters 36 & 37 Magnetism A brief history Lodestones were found in Greece some 2000 years ago. The Chinese later used them for navigating ships. In the 18th century, Charles Coulomb conducted a study of the forces between lodestones. Magnetism A brief history: Until early 19th century, electricity and magnetism were considered to be separate fields. Hans Christian Oersted, in 1820, discovered a relationship between the two during a classroom demonstration. This led to new technology that would bring electric power, radio and television. Magnetic Poles Magnets apply forces on each other similar to charges. Magnets can attract and repel each other. Magnets have poles that are the regions in the magnet that apply forces. Magnetic poles are not positive and negative, but rather North and South. Magnetic Poles There is a rule when it comes to the poles of magnets: Like poles repel; opposite poles attract. Magnetic Poles What would happen if you were to cut a bar magnet in half? Magnetic Field Every magnet produces a magnetic field. A magnet’s magnetic field is similar to a planet’s gravitational field. When another magnet is near, or even a compass, it will lie in a line with the magnetic field. Similarly, iron filings become tiny bar magnets in the presence of a magnetic field. Magnetic Field What did we learn in our lab about the shape of a magnetic field around a bar magnet? Magnetic Field What did we learn about the direction of the magnetic field lines around a bar magnet? Field lines go out from the North and into the South. Magnetic Field What would happen to the magnetic fields of two like poles placed next to each other? N N Magnetic Field What would happen to the magnetic fields of two like poles placed next to each other? N N Magnetic Field What would happen to the magnetic fields of two opposite poles placed next to each other? N S Magnetic Field What would happen to the magnetic fields of two opposite poles placed next to each other? N S Magnetic Field What can you tell about the two magnets in each of these situations? Earth’s Magnetic Field This is a drawing of Earth’s magnetic field and its direction. What do you notice? So which magnetic pole is which? Magnetic Domains Magnetic domains = a microscopic cluster of atoms with their magnetic fields aligned. Magnetic Domains In our lab yesterday, how were you able to pick up the paperclips with the nail? What did the magnet do to the nail? Induced magnetism = metals (particularly iron) exhibiting magnetic properties due to contact with another magnet. Electric Current & Magnetic Field Remember Oersted? What did he discover during a classroom presentation? A moving charge/current produces a magnetic field, deflecting a compass. No current: Current: Electric Current & Magnetic Field These are examples of a current-carrying wire, a current-carrying loop and a coil of loops. Electric Current & Magnetic Field If a current-carrying wire is bent into a loop, the magnetic field lines bunch up. If you add another loop and another, the magnetic field becomes more and more concentrated. This coil is called an electromagnet. Magnetic Force A magnetic field applies a force on a moving charge. Magnetic Force The magnetic field of Earth deflects many charged particles that make up cosmic radiation. Van Allen Belts • The Van Allen radiation belts are formed as a result of earth’s magnetic field and shield us from radiation. We can see the aurora borealis as a result. Magnetic Force A magnetic field will also apply a force on a current-carrying wire. To determine direction, we use the Right Hand Rule. Magnetic Force Let’s try another one… Thumb points in direction of current. Fingers point in direction of magnetic field. Palm points in direction of force. Magnetic Force Give this one a try: I N S Force: into the page Magnetic Force N S I Force: out of the page Magnetic Force N S X I Force: down A Simple DC Motor A Simple DC Motor Electromagnetic Induction Faraday discovered that electric current could be produced in a wire simply by moving a magnet in and out of a coil of the wire. This is called electromagnetic induction. Electromagnetic Induction The greater the number of loops of wire that move in a magnetic field, the greater the induced voltage and the greater the current in the wire.