Electromagnetism

Transformer A static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction, without changing frequency. It consists of two coils (primary and secondary) wound on a common ferromagnetic core. The primary coil is connected to an AC source, creating a changing magnetic flux in the core. This flux links the secondary coil, inducing an EMF by Faraday’s law. Transformers are essential for efficient power transmission over long distances. Step-Up and Step-Down Transformers A step-up transformer increases voltage (secondary turns > primary turns); a step-down transformer decreases voltage (secondary turns < primary turns). The turns ratio determines the voltage transformation. Step-up transformers are used at power stations to raise voltage for transmission, reducing current and thus resistive losses in cables. Step-down transformers near consumers reduce voltage to safe, usable levels (e.g., 230 V in Sri Lanka).