Transformers (Cambridge O Level Physics)

Revision Note

Test yourself
Leander

Author

Leander

Last updated

Transformer

  • A transformer is an electrical device that can be used to increase or decrease the potential difference of an alternating current (voltage transformations)
    • This is achieved using the generator effect

  • A basic transformer consists of:
    • A primary coil
    • A secondary coil
    • soft iron core

  • Iron is used because it is easily magnetised

Structure of a Transformer

Transformer Diagram, downloadable AS & A Level Physics revision notes

Structure of a transformer consists of a soft iron core, and a primary and secondary coil

  • An alternating current is supplied to the primary coil
  • The current is continually changing direction
    • This means it will produce a changing magnetic field around the primary coil

  • The iron core is easily magnetised, so the changing magnetic field passes through it
  • As a result, there is now a changing magnetic field inside the secondary coil
    • This changing field cuts through the secondary coil and induces a potential difference

  • As the magnetic field is continually changing the potential difference induced will be alternating
    • The alternating potential difference will have the same frequency as the alternating current supplied to the primary coil

  • If the secondary coil is part of a complete circuit it will cause an alternating current to flow

Step-up & Step-down Transformers

  • A transformer consists of a primary and secondary coil
    • The primary coil is the first coil
    • The second coil is the second coil
  • A step-up transformer increases the potential difference of a power source
    • A step-up transformer has more turns on the secondary coil than on the primary coil (Ns > Np)
  • A step-down transformer decreases the potential difference of a power source
    • A step-down transformer has fewer turns on the secondary coil than on the primary coil (Ns < Np)

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Leander

Author: Leander

Expertise: Physics

Leander graduated with First-class honours in Science and Education from Sheffield Hallam University. She won the prestigious Lord Robert Winston Solomon Lipson Prize in recognition of her dedication to science and teaching excellence. After teaching and tutoring both science and maths students, Leander now brings this passion for helping young people reach their potential to her work at SME.