• 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_p is input voltage
  • N_p is the number of winding in the primary coil
• 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
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• These are the equations of transformers.
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  • 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.

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_pI_p = V_sI_s

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