Applications of EM Induction

• What is induced in a straight conducting rod moving through a magnetic field?

  e.m.f
• When is e.m.f induced in a conductor moving through a magnetic field?

  When it moves perpendicular to magnetic field lines
• What is the formula for the distance travelled by a conductor?

  s = vΔt
• What does the variable 's' represent in the equation s = vΔt?

  Distance travelled (m)
• What is the area A of the magnetic flux that a conductor cuts through?

  A = LvΔt
• What does ΔΦ represent in the context of magnetic flux?

  Total flux the conductor cuts through
• What is the formula for the total flux ΔΦ that a conductor cuts through?

  ΔΦ = BA = BLvΔt
• What does Faraday's law state about induced e.m.f?

  It is proportional to the rate of change of magnetic flux
• What is the induced e.m.f in a conductor moving through a magnetic field?

  ε = BLv
• What factors increase the induced e.m.f in a conductor?

  Longer conductor, stronger magnetic field, faster movement
• How does the induced e.m.f change with the length of the conductor?

  • Increases with longer conductor
  • Decreases with shorter conductor
• How does the induced e.m.f change with magnetic field strength?

  • Increases with stronger magnetic field
  • Decreases with weaker magnetic field
• How does the induced e.m.f change with the speed of the conductor?

  • Increases with faster movement
  • Decreases with slower movement
• What is the strength of the Earth's magnetic field at the aeroplane's location?

  0.06 mT
• How do you calculate the induced e.m.f between the wing tips of the aeroplane?

  Use ε = BLv
• What happens to e.m.f when a coil rotates in a magnetic field?

  • e.m.f changes as the coil rotates
  • Maximum e.m.f occurs when cutting most field lines

  
• What is the relationship between e.m.f and flux linkage in a rotating coil?

  e.m.f is the rate of change of flux linkage

  
• When is the maximum e.m.f induced in a rotating coil?

  When the coil cuts through most field lines
• What is the phase relationship between e.m.f and flux linkage?

  90° out of phase

  
• What does the equation NΦ = BAN cos(ωt) represent?

  Flux linkage in a rotating coil

  
• What does the angle θ depend on in the equation θ = ωt?

  Angular speed of the coil
• What does the induced e.m.f depend on according to Faraday's Law?

  Rate of change of flux linkage
• What is the formula for the maximum e.m.f induced in a coil?

  ε = BANω

  
• When does the maximum e.m.f occur in a rotating coil?

  When sin(ωt) = ±1
• What is the relationship between the plane of the coil and the magnetic field lines for maximum e.m.f?

  • Maximum e.m.f when coil is parallel to field lines
  • Minimum e.m.f when coil is perpendicular to field lines

  
• What should you remember about e.m.f and flux linkage in terms of their maximum values?

  • e.m.f is maximum when flux linkage is zero
  • Flux linkage is maximum when e.m.f is zero

  
• What should you ensure about your calculator when using angular speed in calculations?

  • Ensure calculator is in radians mode