* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Electromagnetism
Edward Sabine wikipedia , lookup
Geomagnetic storm wikipedia , lookup
Skin effect wikipedia , lookup
Maxwell's equations wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Friction-plate electromagnetic couplings wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Electromotive force wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Magnetometer wikipedia , lookup
Magnetic monopole wikipedia , lookup
Electric machine wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetoreception wikipedia , lookup
Superconducting magnet wikipedia , lookup
Lorentz force wikipedia , lookup
Electromagnetic field wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Magnetotellurics wikipedia , lookup
Electromagnetism wikipedia , lookup
Magnetochemistry wikipedia , lookup
Force between magnets wikipedia , lookup
Faraday paradox wikipedia , lookup
Electromagnet wikipedia , lookup
Ferromagnetism wikipedia , lookup
Electromagnetism Electromagnetism Electricity and magnetism are closely linked. Actual Path of Action Lorentz Force N S - Electron An electric charge moving near a magnet is deflected by an electromagnetic force (Lorentz force). Electron Beam Lorentz Force Electron beam in a Crooke’s tube is deflected when a magnet is brought near the tube. Lorentz Force Old-style TV with a cathode ray tube is distorted by a magnet since the picture is made by electron beam. Lorentz Force When an electric current is flowing in the wire, the magnet exert a force on moving charges. Electromagnetic Induction Voltage and current are induced when a magnet moves towards or away from a coil of wire. Faster the magnet’s motion, the greater the current. Moving in Moving out Electromagnetic Induction Electric current is induced when a magnet moves near a coil of wire. Faster the magnet’s motion, the greater the induced current. AC Electromagnet An electromagnet with an alternating current (AC) makes an oscillating magnetic field. This magnetic field will produce electric currents in objects. Oscillating Magnetic Field Metal ring is heated by the current (Ohmic heating) ElectroMagnet Connect to alternating current (AC) Induction by AC Electromagnet Oscillating magnetic field induces a current in the coil of wire, which lights the small bulb. Coil with bulb Alternating Current (AC) Electromagnet EMP (ElectroMagnetic Pulse) A strong, rapidly fluctuating magnetic pulse induces high voltage, causing strong electrical currents. In 1962, a nuclear test in the Pacific produced an EMP that knocked out 300 streetlights and telephone service in the Hawaiian islands, 900 miles from the explosion. Starfish Prime, as seen from Honolulu EMP in Films EMP is a popular plot device in films. Self-Induction When a current is induced by a changing magnetic field, that current itself produces its own magnetic field. This effect is called self-induction. Oscillating Magnetic Field Current Self-Induced Magnetic Field Magnetic Levitation Induced current produces a secondary magnetic field that is always opposed to the primary magnetic field that induced it, an effect called Lenz’s law. Oscillating Magnetic Field Metal ring is levitated by self-induced secondary magnetic field ElectroMagnet Connect to alternating current (AC) Magnetic Levitation Current is induced in the ring. Magnetic Levitation Ring is cut so current can’t flow. Magnetic Brakes Strong magnet dropped into a copper pipe falls slowly due to secondary magnetic field induced by its motion. Great America’s Drop Zone has a 22 story freefall, lasting four seconds, decelerated by magnetic braking. Magnetic Brakes Strong magnet dropped into a copper pipe falls slowly due to secondary magnetic field induced by its motion. Magnetic Brakes Strong magnet dropped into a copper pipe falls slowly due to secondary magnetic field induced by its motion. Electromagnetic Waves Oscillating electric (E) and magnetic (B) fields produce electromagnetic waves, such as radio waves, microwaves, and visible light. Electromagnetic waves are transverse waves. Summary • Moving electrical charges experience a force from a magnetic field, called the Lorenz force. • A changing magnetic field induces a voltage creating an current in a circuit, an extreme example is an EMP (ElectroMagnetic Pulse). • An induced current produces its own secondary magnetic field (Self-induction). • The magnetic field resulting from an induced current is always opposite from the magnetic field that induced it (Lenz’s Law). • Oscillating electric and magnetic fields produce electromagnetic waves (e.g., light).