# Unit 3- Transformers

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1. Why do direct currents not work with transformers?
Transformers need a changing magnetic field in order to induce a potential difference across the coils. A direct current would make the field only go one way and would not allow a potential difference to be induced across the coils. So the transformer would not work with a direct current
2. How do transformers work?
• Transformers work by electromagnetic induction. The primary coil produces a magnetic field that stays within the iron core.
• Because there is an alternating current in the primary coil, the magnetic field in the iron constantly changes. This induces a alternating potential difference across the secondary coil.
3. How many turns are there on the primary and secondary coil in a STEP-UP transformer and why?
There are MORE turns on the secondary coil that the primary coil because the VOLTAGE IS INCREASED.
4. How many turns are there on the primary and secondary coil in a STEP-DOWN transformer and why?
There are MORE turns on the primary coil and less on the secondary because the VOLTAGE IS DECREASED
 Author: Anonymous ID: 296749 Card Set: Unit 3- Transformers Updated: 2015-02-24 19:26:05 Tags: unit3 transformers Folders: GCSE Physics Description: information about transformers and electromagnetic fields Show Answers: