T6: magnets

• construction of electromagnets: soft iron core wrapped in wire = current in wire causes it to become magnetic
• right hand rule: thumb = direction of current, fingers = direction of magnetic field lines
• movement of charged particles = current - produces magnetic field

  • reacts with permanent magnets to create a force = perpendicular to motion
• structure of transformer:

  • AC current in primary coil = changing magnetic field
  • iron core channels changing field through secondary coil
  • changing field induces voltage in secondary coil
• step up transformers = increase voltage = more secondary coils that primary
• step down transformers = decrease voltage = more primary coils that secondary
• input voltage / output voltage = primary turns / secondary turns
• input power = output power - 100% efficiency