7.3.2

Transformers 2

Test yourself

Step-Up and Step-Down Transformers

Transformers are separated into step-up transformers and step-down transformers.

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Step-up transformer

  • Ns > Np .
  • The secondary coil has more turns than the primary coil.
  • The potential difference across the secondary coil is greater than the potential difference across the primary coil. (The potential difference is ‘stepped up’.)
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Step-down transformer

  • Ns < Np .
  • The secondary coil has fewer turns than the primary coil.
  • The potential difference across the secondary coil is less than the potential difference across the primary coil. (The potential difference is ‘stepped down’.)

Principles of Transformer Operation

Transformers work like this:

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Alternating potential difference (p.d)

  • An alternating p.d (p.d that is constantly changing direction) is applied to the primary coil of the transformer.
  • This alternating p.d causes an alternating current to flow through the primary coil.
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Changing magnetic field

  • The alternating current creates a continuously changing magnetic field in the iron core of the transformer.
  • The changing magnetic field in the iron core also passes through the secondary coil.
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Secondary coil potential difference (p.d)

  • The changing magnetic field passing through the secondary coil induces an alternating p.d in the secondary coil.

Jump to other topics

1Energy

2Electricity

3Particle Model of Matter

4Atoms & Radiation

5Forces

6Waves

7Magnetism

8Astrophysics

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