KS5 Electromagnetism

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Electromagnetism - Objectives




  • Force on a current-carrying wire in a magnetic field: F = BIl when field is perpendicular to current.
  • Fleming’s left hand rule.
  • Magnetic flux density B and definition of the tesla.
  • Force on charged particles moving in a magnetic field, F = BQv when the field is perpendicular to velocity.
  • Direction of force on positive and negative charged particles.
  • Circular path of particles; application in devices such as the cyclotron.
  • Magnetic flux defined by φ = BA where B is normal to A.
  • Flux linkage as Nφ where N is the number of turns cutting the flux.
  • Flux and flux linkage passing through a rectangular coil rotated in a magnetic field:
  • flux linkage Nφ = BANcosθ
  • Simple experimental phenomena.
  • Faraday’s and Lenz’s laws.
  • Magnitude of induced emf = rate of change of flux linkage
  • Ɛ = N ∆ φ/∆ t
  • Applications such as a straight conductor moving in a magnetic field.
  • emf induced in a coil rotating uniformly in a magnetic field:
  • Ɛ = BANω sin ωt
  • Sinusoidal voltages and currents only; root mean square, peak and peak-to-peak values for sinusoidal waveforms only.
  • Irms = I0/√2 ; Vrms = V0/√2
  • Application to the calculation of mains electricity peak and peak-to-peak voltage values.
  • Use of an oscilloscope as a dc and ac voltmeter, to measure time intervals and frequencies, and to display ac waveforms.
  • No details of the structure of the instrument are required but familiarity with the operation of the controls is expected.
  • The transformer equation: Ns/Np = Vs/Vp
  • Transformer efficiency =ISVS/IPVP
  • Production of eddy currents.
  • Causes of inefficiencies in a transformer.
  • Transmission of electrical power at high voltage including calculations of power loss in transmission lines.

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