5.1 and 5.2 Magnetic Forces on Moving Charges

Current Carrying Conductors

  • magnetic fields can be produced by movement of charged particles - usually electrons in wires
    • straight wire produces magnetic field of circles around it when current flows up through it
  • current is the direction of CONVENTIONAL CURRENT (POSITIVE TO NEGATIVE), not electron flow so flip hand around
  • not a dipole field - two charges with same but opposite charges placed near each other

Magnetic Force on Currents

  • when a current moves through a wire in a pre-existing magnetic field, a force is exerted on the wire as the magnetic fields interact
  • factors affecting:
    • amount of current
    • length of wire
    • magnetic flux density of the field
    • angle between the wire and the field - if angle is 90 = max force, if angle is 0 = minimum force
  • referred to as Lorentz force

Magnetic Force on Particles

  • force experienced by wire is combo of forces experienced by individual charges within it
  • if charge isn’t stuck in a wire use F = qvBsin𝜽
    • this is the magnetic force
  • current is replaced with velocity