Physics ii


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Physics ii

  1. 1. How Electric Motors Work Introduction An electric motor works because its insides contain both magnetism and magnets. An electric motor uses the magnets to power its motion. Magnets have the ability to both repel and attract one another. In fact, the fundamental law of all magnets states that opposites attract and likes repel. There are two ends to each magnet: one end is marked "north," and the other end is marked "south." The south end of a magnet is attracted to the north end of the other magnet and repels against the other magnet's south end. The same is true for the north end; it wants to connect to the other magnet's south end and repels against its north end. Principals The main source of power of an electric motor is its electromagnet. The electromagnet is wrapped around coil and is placed in the middle of the axle. The axle is a magnet as well. A battery is attached to the electromagnet, and its ends repel against the ends of axle causing it to begin turning. This begins to cause motion, and the electric motor begins to spin freely, giving it power.
  2. 2. Parts A basic electric motor contains six different parts: armature, brushes, commutator, field magnet, axle and power supply. The axle in an electric motor holds the commutator and the armature. The armature is a set of electromagnets that cause the motor to work. The armature consists of a group of thin metal plates stacked on top of each other. A thinly cut copper wire is coiled around each one, and each end of the copper wire is soldered. Each of the metal plates is wired to the commutator. The electric field begins to work in two parts. When the contacts of the commutator attach to the electromagnet's axle, they begin to the spin magnets. The brushes are made of springy metal that make a connection with the contacts of the commutator. The field magnet is placed inside and may include two additional magnets to work in correlation. The ends of the magnets rest against the sides and work with the rest of the parts to make the electric motor work.
  3. 3. How Generator works A.C Generator The purpose of a generator is to convert motion into electricity. This wouldn't be possible if it wasn't for one fact: That a wire passing through a magnetic field causes electrons in that wire to move together in one direction. A generator consists of some magnets and a wire (usually a very long one that's wrapped to form several coils and known as an armature). A steam engine or some other outside source of motion moves the wire or armature through the magnetic field created by the magnets. In the example to the left, a loop of wire is spinning within a magnetic field. Because it is always moving through the field, a current is sustained. But, because the loop is spinning, it's moving across the field first in one direction and then in the other, which means that the flow of electrons keeps changing. Because the electrons flow first in one direction and in the other, the generator produces an alternating current. One advantage that AC has over DC is that it can easily be "stepped up" or "stepped down" with a transformer. In other words, a transformer can take a low-voltage current and make it a high- voltage current, and vice versa. This comes in handy in transmitting electricity over long distances. Since AC travels more efficiently at high voltages, transformers are used to step up the voltage before the electricity is sent out, and then other transformers are used to step down the voltage for use in homes and businesses. A loop of wire spinning through a magnetic field will create an alternating current. Note: current will flow only if the circuit connected to the generator is complete.
  4. 4. D.C Generator An electrical generator is a device that converts mechanical energy to electrical energy, generally using electromagnetic induction. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, or any other source of mechanical energy. The Dynamo was the first electrical generator capable of delivering power for industry. The dynamo uses electromagnetic principles to convert mechanical rotation into an alternating electric current. A dynamo machine consists of a stationary structure which generates a strong magnetic field, and a set of rotating windings which turn within that field. On small machines the magnetic field may be provided by a permanent magnet; larger machines have the magnetic field created by electromagnets. The energy conversion in generator is based on the principle of the production of dynamically induced e.m.f. Whenever a conductor cuts magneticic flux , dynamically induced e.m.f is produced in it according to Faraday's Laws of Electromagnetic induction.This e.m.f causes a current to flow if the conductor circuit is closed. Hence, two basic essential parts of an electrical generator are (i) a magnetic field and (ii) a conductor or conductors which can so move as to cut the flux.
  5. 5. How Electric Motor Works Electric motors are everywhere! In your house, almost every mechanical movement that you see around you is caused by an AC (alternating current) or DC (direct current) electric motor. A simple motor has six parts: Armature or rotor Commutator Brushes Axle Field magnet DC power supply of some sort By understanding how a motor works you can learn a lot about magnets, electromagnets and electricity in general. In this article, you will learn what makes electric motors tick.
  6. 6. Electromagnetic Induction Electromagnetic induction (or sometimes just induction) is a process where a conductor placed in a changing magnetic field (or a conductor moving through a stationary magnetic field) causes the production of a voltage across the conductor. This process of electromagnetic induction, in turn, causes an electrical current - it is said to induce the current. Michael Faraday is given credit for the discovery of electromagnetic induction in 1831, though some others had noted similar behavior in the years prior to this. The formal name for the physics equation that defines the behavior of an induced electromagnetic field from the magnetic flux (change in a magnetic field) is Faraday's law of electromagnetic induction.
  7. 7. Hydraulic power plants In power station require the installation of large equipment such as water turbines, generators, transformers, and overhead cranes, as well as piping and electrical construction. Hydraulic power station uses clean energy to supply electrical power. We install water turbines and generators, these are major equipment in power stations in both Japan and overseas. We apply its technical construction capabilities in the construction of large water pumps as well as wind turbine. This shows a 216,000-kW water turbine runner being lifted. (Overseas) The weight of the water turbine runner was 180 tons, but there was no lifting equipment at the port near the site, so a ship with a derrick crane was chartered and transported from Japan.
  8. 8. Thermal Power Plant In a conventional thermal power station, a fuel is used to heat water, which gives off steam at high pressure. This in turn drives turbines to create electricity. At the heart of a power stations is a generator, a rotating machine that converts mechanical energy into electrical energy by creating relative motion between a magnetic field and a conductor. The energy source harnessed to turn the generator varies widely. It depends chiefly on which fuels are easily available and on the types of technology used. Thermal power plants are classified by the type of fuel used
  9. 9. Our Lady of Manaoag College Manaoag, Pangasinan Batchelor of Science in Information Technology Research Work In Physics (HEAT, ELESTRICITY, & MAGNITISM) JUSTINE OCAMPO GARCIA BSIT-I 1st Year S.Y. 2012-2013