Solve problems in electromagnet circuits 1

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Solve problems in electromagnet circuits 1

  1. 1. Laws and rules G001B <ul><li>Solve problems in electromagnetic circuits </li></ul>
  2. 2. Right-hand thumb rule (straight conductor) <ul><li>Grasp the conductor in the right hand with the thumb pointing in the direction of current flow. </li></ul><ul><li>The fingers point in the direction in which the magnetic force is acting. </li></ul>Revision02
  3. 3. Right-hand thumb rule (Solenoid) <ul><li>Grasp the solenoid in the right hand so that the fingers point in the direction of current flowing through the coil. </li></ul><ul><li>Extend the thumb at right angles to these fingers and the thumb will point in the direction of the north pole. </li></ul>Revision02
  4. 4. Mangnetmotive Force (mmf) <ul><li>mmf = I.N in amp-turns </li></ul><ul><li>The value of mmf is determined by the number of turns in a coil and the amount of current flowing. To adjust the amount of mmf the current is adjusted. </li></ul>Revision02
  5. 5. Faraday’s law of induced e.m.f. <ul><li>The value of the e.m.f. induced in a circuit depends on the number of conductors in the circuit and the rate of change of the magnetic flux linking the conductors. </li></ul>Revision02
  6. 6. Fleming’s right-hand rule (Generator) <ul><li>Place the thumb, index finger and middle finger of the right hand at right angles [90°] to each other </li></ul><ul><ul><li>Point the thumb to indicate the direction of motion of conductor through the flux </li></ul></ul><ul><ul><li>Point the first finger to indicate the direction of magnetic flux action </li></ul></ul><ul><ul><li>The middle finger will then point in the direction in which the induced e.m.f. acts along the conductor </li></ul></ul>Revision02
  7. 7. Fleming’s left-hand rule (Motor) <ul><li>Place the thumb, index finger and middle finger of the left hand at right angles [90°] to each other </li></ul><ul><ul><li>Point the first finger to indicate the direction of magnetic flux action. </li></ul></ul><ul><ul><li>Point the middle finger in the direction of current flow in the conductor. </li></ul></ul><ul><ul><li>The thumb now indicates the direction in which the force is exerted on the conductor. </li></ul></ul>Revision02
  8. 8. Lenz’s Law <ul><li>The direction of an induced e.m.f. is such that the resulting current flow will produce a magnetic field which tends to oppose the original motion causing the induced e.m.f. </li></ul>Revision02

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