Electromagnetism ch 20

• Right hand grip rule- thumb represents direction of current flow, other finger curl to represent direction of magnetic field
• Reversing the direction of current reverses the direction of magnetic field
• Strength of magnetic field increases when current increases
• The strength of the magnetic field decreases as distance from the wire increases
• field produces by current is temporary
• Increasing strength of magnetic field in a solenoid:

  1. increase current flowing through the solenoid
  2. increase number of turns per unit length of solenoid (increase number of coils around solenoid )
  3. placing soft iron core within the solenoid( concentrates magnetic field thus strengthening it)
• Increasing current in current-carryng conductor produces larger swing
• increasing strength of magnetic field produces a larger swing in current-carrying conductor
• reversing direction of current in a current-carrying conductor induces a swing in the opposite direction
• Fleming’s left hand rule:

  thumb= force (motion)

  Index finger= magnetic field ( closest to thumb is north)

  middle finger=direction of current of wire ( closest to thumb is positive )