3. Transformers

Concept Explanation:
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Transformers are essential for the transmission of AC electrical power over long distances.

Working Principle:
The transformer operates on the principle of mutual inductance between two coils, known as the primary and secondary windings. When an AC voltage is applied to the primary winding, it creates a changing magnetic field, which induces a voltage in the secondary winding.

Transformer Equations:
The voltage ratio between the primary and secondary windings is given by:
V_p / V_s = N_p / N_s
where:
- V_p and V_s are the voltages across the primary and secondary windings, respectively,
- N_p and N_s are the number of turns in the primary and secondary windings, respectively.

The power transferred is given by:
P_p = P_s
V_p × I_p = V_s × I_s
where I_p and I_s are the currents in the primary and secondary windings, respectively.

Example Problem:
A transformer has 500 turns on its primary coil and 100 turns on its secondary coil. If the primary voltage is 240 V, calculate the secondary voltage.

Solution:
Using the transformer equation:
V_p / V_s = N_p / N_s
240 / V_s = 500 / 100
V_s = 240 × 100 / 500 = 48 V