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- By using Faraday’s Law of induction, It can be shown that the rate of change of flux due to an alternating input current is :
- where
*V*is input voltage_{p} *N*is the number of winding in the primary coil_{p}

- where
- By using Faraday’s Law of induction, It can be shown that the voltage developed in the secondary coil due to changing flux experience is :
- In an ideal transformer, changing flux that is experienced by the secondary coil is the same changing flux due to the primary coil.
- Therefore
- These are the equations of transformers.
- If N
_{s}is greater than N_{p}, then it is known as Step-Up transformer - If N
_{s}is smaller than N_{p}, it is known as Step-Down Transformer.

- If N

Energy conservation in an Ideal Transformer

- Energy is transferred from the primary coil to the secondary coil.
- In an ideal transformer, there is no loss during this transfer of energy.
- If there is no loss , then power in the secondary and primary coil are same.
- Equation of power :
*P = VI* - Thus,
*V*_{p}I_{p}= V_{s}I_{s}

- Equation of power :

- This allows us to understand how low voltage in input coil can give higher voltage on output coil in Step-Up Transformer

Extract from *Physics Stage 6 Syllabus © 2017 *NSW Education Standards Authority (NESA)