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  1. 1. ELECTROMAGNETISM<br /> By: <br />Joshua Alfred De la Cruz<br />Nicole Marie Dela Cruz<br />Stephen Miayo<br />
  2. 2. History<br />The origin of electricity is and magnetism sprang from ancient men’s curiosity over the ability of two materials, amber and lodestone to attract other materials.<br />With the publication of James Clerk Maxwell's 1873 Treatise on Electricity and Magnetism in which the interactions of positive and negative charges were shown to be regulated by one force.<br />
  3. 3. History<br />There are four main effects resulting from these interactions, all of which have been clearly demonstrated by experiments:<br />Electric charges attract or repel one another with a force inversely proportional to the square of the distance between them: unlike charges attract, like ones repel.<br />
  4. 4. History<br />Magnetic poles attract or repel one another in a similar way and always come in pairs: every north pole is yoked to a south pole.<br />An electric current in a wire creates a circular magnetic field around the wire, its direction depending on that of the current.<br />
  5. 5. History<br />A current is induced in a loop of wire when it is moved towards or away from a magnetic field, or a magnet is moved towards or away from it, the direction of current depending on that of the movement.<br />
  6. 6. Magnetism<br />It is the term used to refer to the ability of lodestones to attract iron.<br />A material having this property is called a magnet.<br />The modern name for lodestone or magnetic iron ore is magnetite.<br />
  7. 7. Classification<br />Natural<br />They are found in nature and are called lodestones or magnetite.<br />Artificial<br />May be temporary or permanent.<br />Retentivityis the ability of a magnetic material to retain its magnetism after it has been magnetized.<br />
  8. 8. Classification<br />Electromagnet<br />A magnet whose magnetic field is produced by electric current passing through coils of wire wrapped around a core.<br />
  9. 9. Types<br />Ferromagnetism<br />Are strongly attracted be a magnet.<br />They include iron, cobalt, nickel, and steel.<br />In ferromagnetic materials, all electrons are spinning in the same direction.<br />Diamagnetism<br />Is a weak response to magnetic field.<br />Materials are repelled by a magnetic field.<br />Metals, like bismuth, copper, gold, silver, lead, nonmetals, water, and organic compounds are diamagnetic.<br />
  10. 10. Types<br />Paramagnetism<br />Weakly attracted to magnets.<br />When cooled, more magnetic.<br />
  11. 11. Geomagnetism<br />Referred as Earth’s magnetism.<br />William Gilbert- conducted experiments and concluded that the Earth was a huge magnet.<br />
  12. 12. Law of Magnetic Poles<br />Peter Petegrinus- same poles repel.<br />William Gilbert- confirmed it.<br />John Michael- force of attraction or repulsion between poles varies inversely as the square of the distance between them.<br />
  13. 13. Law of Magnetic Poles<br />Charles de Coulomb- force between two poles is directly proportional to the product of the poles and inversely proportional to the square of the distance between them.<br />By combining these relation, he proposed the equation:<br />m1m2<br /> F= k<br />d2<br />Where F is the force, k as the constant, m are pole strengths in ampere, and d is the distance in meters.<br />
  14. 14. Magnetic Field<br />Is a region of space where a magnet is capable of exerting a force on a magnetic material.<br />Analogous to the electric field around an electric charge.<br />
  15. 15. Magnetic Field<br />Is also defined in terms of the force exerted on an electric charge moving in the field.<br />Michael Faraday- introduced the idea that the magnetic field is made up of lines of force which is called the magnetic flux.<br />
  16. 16. Magnetic Field<br />Magnetic flux- it’s unit is weber(Wb), flux per unit area perpedicular to tefiel is called magnetic field intensity– the SI unit for I is tesla. Named afte Nikola tesla.<br />
  17. 17. Magnetic Effect of Current<br />ChistianOersted- made a demonstration on the heating effect of a current.<br />by this , he accidentally discovered that a current-carrying conductor produces a magnetic field and this was influenced the orientation of the nearby compass.<br />right hand rule- the magnetic field produced by a current may be determined by this.<br />
  18. 18. The Electromagnet<br />A magnet whose magnetic field is produced by electric current passing through coils of wire wrapped around a core and the strength depends on the number of turns and current.<br />The first ever electromagnet was made by William Sturgeonand later improved by Joseph Henry.<br />
  19. 19. Uses<br />They can be turn on/off.<br />The strength can be varied.<br />Very large magnetic field can be produced.<br />Used in steel yards.<br /> Essential parts in the construction of electric meters, electric generators, circuit breakers, motors and others.<br />
  20. 20. Electromagnetic Induction<br />Process by which a changing magnetic flux produces electric current.<br />The current and emf produce is called induced current an induces emf.<br />There are two laws describing the electromagnet induction: Faraday’s law and Lenz’s law.<br />
  21. 21. Electromagnetic Induction<br />Faraday’s law-states that whenever there is a change in the magnetic flux in a circuit, an induced current is produce.<br />Lenz’s law- states that the induced current flows in a direction so as to oppose the change causing it.<br />
  22. 22. Application <br />Discovery of Faraday and Henry paved the development of the generator, transformer and other devices that made the production of electricity cheaper.<br />
  23. 23. AC/DC Generator<br />Converts mechanical energy to electrical energy.<br />HyppolytePixii- was credited for having made the first electric generator.<br />
  24. 24. Parts of a Simple AC generator<br />armature- consist of coils of insulated wire wound around a soft iron core.<br /> - attached to a shaft so that it can rotate between the poles of the magnet.<br /> - ends are connected to the external circuit by means of slip rings that rotate with the armature.<br />
  25. 25. Parts of a Simple AC generator<br />Slip rings- made of either brass or copper.<br /> - insulated from each other and from he shaft.<br /> - each rings slides against the stationary brush . <br />Brush- collect the current and transmit it to the external circuit.<br />
  26. 26. Motor<br />A generator operating reverse.<br />Changes electrical energy to mechanical energy.<br />Has the same parts as a simple DC generator.<br />
  27. 27. Parts of a Motor<br />Brushes are connected to a battery to send current to the armature.<br />Magnetic field produced by this current in the armature interacts with the field of the magnet and exerts a force that rotates the armature.<br />A shaft attached to the armature makes the motion for doing work.<br />
  28. 28. Parts of a Motor<br />
  29. 29. Transformer<br />a device used to raise or lower the voltage of an AC source.<br />consist primary and secondary coils placed side by side having a common iron core.<br />
  30. 30. Transformer<br />Plays a major role in power transmission.<br />Whenever electricity is transmitted , there is always loss of power because of the resistance of the transmission wires.<br />
  31. 31. Types of Transformer<br />Step down transformer- lowers the voltage.<br />Step up transformer- raises the voltage.<br />
  32. 32. THANK YOU!<br /> THE END…<br />