RP11 - Magnetic Flux Linkage

Cards (12)

  • What pieces of apparatus can be used to measure the induced emf inside a current carrying circular coil?
    A search coil connected to an oscilloscope
  • Why must an alternating current source be used in this experiment?
    An AC source should be used so that the magnetic flux through the search coil is constantly changing
  • How can an oscilloscope be used to measure the induced EMF?
    • When connected to the search coil, the oscilloscope will show the waveform of the induced EMF
    • By turning the time base off, this will become a vertical line that gives the peak to peak value of the EMF
  • What preliminary experiment will need to be undertaken before carrying this experiment out?
    • A preliminary experiment will be needed to determine a suitable voltage and frequency for the circular coil
    • The induced emf must be large enough to be easily measured using the search coil and oscilloscope
  • What is magnetic flux?
    • Magnetic flux is equal to the product of the magnetic flux density and the area through which it passes
    • It can be thought of as the number of field lines passing through a given area
  • Suggest how angle measurements could be taken in this experiment
    • A circular protractor card could be positioned under the circular coil and fixed in place with an optical pin
    • This allows the angle between the circular coil and the search coil to be measured from the same position each time
  • In what orientation will the maximum induced EMF and flux linkage occur in the search coil?
    • The maximum induced emf and flux linkage will occur when the search coil is perpendicular to the magnetic field lines
    • This is when the angle is equal to 0 degrees
  • Why might an ammeter be required when carrying out the preliminary experiment?
    • It is important to ensure that the current passing through the coil doesn't exceed the manufacturer's guidelines
  • In which orientation should the induced EMF be at a minimum?
    • The induced EMF should be zero when the search coil is parallel to the magnetic field lines
    • This is when the angle is equal to 90 degrees
  • What is magnetic flux linkage?
    Magnetic flux linkage is equal to the magnetic flux passing through a coil multiplied by the number of turns that cut this flux
  • What is the unit of magnetic flux?
    Webers (Wb)
  • Gradient Derivation:
    N = BANcos (x)
    I = I_0cos(ωt) + B = B_0cos(ωt)
    N = BANcos(x) = B_0cos(ωt)ANcos(x)
    E = ΔN /Δt = - B_0ANΔsin(ωt)cos(x)
    E_0 = B_0ANω cos(x) when sin (ωt) = 1 or -1
    Where:
    E_0 = y
    B_0ANω = x
    cos(x) = m