Electromagnetism

• Electromagnetism is the phenomenon where electric currents produce their own magnetic fields
• Magnetic field around a wire with current flowing from bottom to top is represented by concentric circles closest together near the wire
• Right hand rule: thumb points in the direction of current flow, fingers curling in tell the direction of the magnetic field
• For wires with opposite currents, magnetic fields travel in opposite directions
• Flat circular coil with current flowing in creates a single magnetic field through the center, forming ellipses
• Adding more turns to a coil creates a solenoid with a strong and uniform magnetic field inside
• Outside the solenoid, the magnetic field is similar to that of a bar magnet with north and south poles
• Electromagnets are only magnetic when current flows through the wire
• To increase electromagnet strength:

  • Increase the current flowing through the solenoid
  • Increase the number of turns in the coil
  • Decrease the length of the coil
  • Add an iron core inside the solenoid to increase the strength of the magnetic field