# Analyse quantitatively the operation of ideal transformers

• 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 Vp is input voltage
• Np 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
• These are the equations of transformers.
• If Ns is greater than Np, then it is known as Step-Up transformer
• If Ns is smaller than Np, 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, VpIp = VsIs
• 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)