Transformers

Transformers

1. What?

   • A transformer is a piece of machinery that induces a higher voltage to an alternating current
     • It consists of two coils (primary and secondary) which are joined with an iron core, with an alternating current.
       • The primary coil has more turns on a step-down transformer than the secondary coil
       • The primary coil on a step-up transformer has less turns than the secondary coil
     • They are nearly 100% efficient

2. Where?

   • Transformers are used in the national power grid

3. Why?

   • When a current flows through a wire some energy is lost as heat. The higher the current, the more heat is lost, and the hotter the wire becomes To reduce these losses and the danger of heat electricity is transmitted at a low current which needs a high voltage.
   • These high voltages are too dangerous to use in the home, so step-down transformers are used locally to reduce the voltage to safe levels.

4. How?

   • Transformers change the size of the potential difference of an alternating current
     • When the alternating current is applied across the primary coil, it produces a magnetic field. This induces a alternating magnetic field in the iron core
       • This then induces a potential difference in the secondary coil

5. Formulas

   • Power = Potential difference x Current
   • Potential difference across Primary coil / Potential difference across Secondary coil = Number of turns in Primary coil / Number of turns in Secondary coil