Transcript Chapter #14
Chapter #14 Magnets and Magnetic Fields Chapter 14.1 Notes Magnetic pole an area of a magnet where the magnetic force appears to be the strongest. Magnetic field a region where a magnetic force can be detected. Compass Chapter 14.2 Notes • The right-hand rule: if you imagine holding the wire in your hand with your thumb pointing in the direction of the positive current, the direction your finger would curl is in the direction of the magnetic field. Solenoid a long, wound coil wire resembles the magnetic field of a bar magnet. • Electromagnet a strong magnet created when an iron core is inserted into the center of a currentcarrying solenoid. Domain a microscopic magnetic region composed of a group of atoms whose magnetic fields are aligned in a common direction. Galvanometer an instrument that measures the amount of current in a circuit. • Electric motor a device that coverts electrical energy to mechanical energy. Chapter 14.3 Notes • Electromagnetic induction the production of a current in a conducting circuit by a change in the strength, position, or orientation of an external magnetic field. • Faraday’s law states that an electric current can be produced in a circuit by a changing magnetic field. Faraday wondered Can magnetism produce electricity? He discovered that a moving magnet can induce an electric current in a wire. Michael Faraday Don’t need to write in notes!!! • A Faraday cage or Faraday shield is an enclosure formed by conducting material, or by a mesh of such material. Such an enclosure blocks out external static electrical fields. Faraday cages are named after physicist Michael Faraday, who built one in 1836 • An external static electrical field will cause the electrical charges within the conducting material to redistribute themselves so as to cancel the field's effects in the cage's interior. This effect is used, for example, to protect electronic equipment from lightning strikes and other electrostatic discharges. Faraday Cage Generator a device that uses electromagnetic induction to convert mechanical energy to electrical energy. Alternating current (AC) an electric current that changes direction at regular intervals. Generator Transformer a device that can change one alternating-current voltage to a different alternating-current voltage. • Step-up transformer • Step-down transformer Work Cited • • • • • • • • • • • • “Earth”. May 27, 2008. http://boojum.as.arizona.edu/~jill/NS102_2004/Lectures/Lecture3/28_03_Earth_ magnetic_field.jpg “Magnets”. May 28, 2008. http://www.physics.sjsu.edu/becker/physics51/images/28_01_Bar_magnets.JPG “Electric Motor”. May 28, 2008. http://web.ncf.ca/ch865/graphics/DCElectricMotor.jpeg “Solenoid”. May 28, 2008. http://web.ncf.ca/ch865/graphics/Solenoid.jpeg “Electromagnet”. May 28, 2008. http://www.bbc.co.uk/schools/ks3bitesize/science/images/sci_dia_79.gif “Galvanometer”. May 28, 2008. http://www.unm.edu/~physics/demo/html_demo_pages/5k1020.jpg “Faraday Cage”. May 29, 2008. http://sprg.ssl.berkeley.edu/~clee/images/traveling/boston/CISM_Summer_Scho ol/Science_Center/faraday_cage1.jpg “Faraday Picture”. May 29, 2008. http://itp.nyu.edu/~nql3186/electricity/images/faraday.gif “Faraday Cage info”. May 29, 2008. http://en.wikipedia.org/wiki/Faraday_cage “Generator”. May 29, 2008. http://sol.sci.uop.edu/~jfalward/physics17/chapter9/generator.jpg “Electrical Transformer”. May 29, 2008. http://72.29.25.240/images/electricaltransformers.jpg “Transformer”. May 29, 2008. http://72.29.25.240/images/electrical-transformerdesign.jpg