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Electromagnetism

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The grade 11 presentation on electromagnetism

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Electromagnetism

  1. 1. 1Everything Science www.everythingscience.co.za10. ElectromagnetismPhysicsGrade 11
  2. 2. 2Everything Science www.everythingscience.co.zaIntroductionElectromagnetism is the study of the properties and relationship between electric currents andmagnetism.A current-carrying conductor will produce a magnetic field around the conductor.
  3. 3. 3Everything Science www.everythingscience.co.zaMagnetic field around a current carrying conductor
  4. 4. 4Everything Science www.everythingscience.co.zaThe Right Hand RuleThe Right Hand Rule says that the magnetic field lines produced by a current-carrying wirewill be oriented in the same direction as the curled fingers of a person’s right hand (in the“hitchhiking” position), with the thumb pointing in the direction of the current flow.
  5. 5. 5Everything Science www.everythingscience.co.zaMagnetic field around a current carrying loop
  6. 6. 6Everything Science www.everythingscience.co.zaMagnetic field around a solenoidIf we now add another loop with the current in the same direction, then the magnetic fieldaround each loop can be added together to create a stronger magnetic field. A coil of manysuch loops is called a solenoid. A solenoid is a cylindrical coil of wire acting as a magnetwhen an electric current flows through the wire.
  7. 7. 7Everything Science www.everythingscience.co.zaMagnetic fluxThe magnetic flux through a surface is the product of the component of the magnetic fieldnormal to the surface and the surface area:Where:θ = the angle between the magnetic field, B, and the normal to the loop of area AA = the area of the loopB = the magnetic fieldThe SI unit of magnetic flux is the weber (Wb)φ=BA cosθ
  8. 8. 8Everything Science www.everythingscience.co.zaElectromagnetic inductionElectromagnetic induction occurs when a changing magnetic field induces a voltage in acurrent-carrying conductor.The magnitude of the induced emf is given by Faraday’s law of electromagnetic Induction:where φ = B·A and B is the strength of the magnetic field. N is the number of circuit loops. Amagnetic field is measured in units of teslas (T). The minus sign indicates direction and thatthe induced emf tends to oppose the change in the magnetic flux. The minus sign can beignored when calculating magnitudes.ℇ=−NΔ φΔt
  9. 9. 9Everything Science www.everythingscience.co.zaFor more practice see:www.everythingscience.co.zaShortcode: ESBQ4
  10. 10. 9Everything Science www.everythingscience.co.zaFor more practice see:www.everythingscience.co.zaShortcode: ESBQ4

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