Question

What is a transformer? Explain the construction and working of a transformer. Derive the equation for a transformer.

Hint:

In an ideal transformer, the power is conserved, meaning \( V_p I_p = V_s I_s \), where \( I_p \) and \( I_s \) represent the primary and secondary currents, respectively.

Answer 1

A transformer is an electrical device designed to alter the voltage and current in an alternating current (AC) circuit. It operates based on the principle of electromagnetic induction. 
Construction: A transformer is made up of: A primary coil (input coil) connected to an AC power source. A secondary coil (output coil) connected to the load. A magnetic core, typically made of iron, that links both coils. 
Working: 
When an alternating current flows through the primary coil, it creates a time-varying magnetic field. This changing magnetic flux links to the secondary coil, inducing an electromotive force (emf) in the secondary coil, as described by Faraday's Law of Induction. 
Equation for Transformer:
The relationship between the voltages and the number of turns in the primary and secondary coils is expressed by the following equation: \[ \frac{V_s}{V_p} = \frac{N_s}{N_p} \] where: 
- \( V_s \) is the secondary voltage, 
- \( V_p \) is the primary voltage, 
- \( N_s \) is the number of turns in the secondary coil, 
- \( N_p \) is the number of turns in the primary coil. \bigskip