Voltage is induced in a transformer primarily due to the principle of electromagnetic induction, specifically mutual induction, governed by Faraday's law. When an alternating current (AC) flows through the primary coil, it creates a changing magnetic flux in the transformer's core. This fluctuating magnetic flux passes through the secondary coil, inducing an electromotive force (EMF) or voltage in it
. Key points explaining this process:
- Faraday's Law of Electromagnetic Induction states that a changing magnetic flux through a coil induces a voltage proportional to the rate of change of the flux
- The alternating current in the primary coil produces a time-varying magnetic field, which is essential since a constant magnetic field (like from DC) would not induce voltage in the secondary coil
- The transformer core (usually iron) enhances the magnetic coupling between the primary and secondary coils, ensuring efficient transfer of magnetic flux and thus voltage induction
- Mutual induction occurs as the magnetic field created by the primary coil induces a voltage in the secondary coil without direct electrical connection
- The magnitude of the induced voltage depends on the number of turns in the coils and the rate of change of the magnetic flux. More turns in the secondary coil relative to the primary coil increase the induced voltage (step-up transformer), and fewer turns decrease it (step-down transformer)
In summary, voltage is induced in a transformer because the alternating current in the primary coil creates a changing magnetic flux in the core, which then induces a voltage in the secondary coil through electromagnetic induction principles
