transformers

• a basic transformer consists of a primary coil and a secondary coil wound on an iron core
• iron is used in transformers because it is easily magnetised
• 1. alternating potential difference is applied across the primary coil
  2. which causes a current to flow and generates a magnetic field around the coil
  3. because the potential difference is alternating, the direction of the magnetic field and current will also alternate
  4. this alternating magnetic field in the primary coil induces an alternating magnetic field around the iron core, as iron is a magnetic material
  5. the iron core's magnetic field induces a potential difference in the secondary coil
  6. because it is part of a complete circuit, this causes a current to flow around the secondary coil
• if the secondary coil has more turns than the primary coil, the induced potential difference will be greater than the potential difference of the primary coil
• if the secondary coil has less turns, the induced potential will be lower than the potential difference of the primary coil
• step-up transformers in the national grid have more turns in the secondary coil than the primary coil, which leads to a greater potential difference in the secondary coil and the power is constant so a lower current