Introduction:

A transformer is a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It is widely used in power transmission and distribution systems to step up or step down voltage levels. Understanding transformers is essential for Class 12 students as it forms a crucial part of the Electromagnetic Induction chapter.



What is a Transformer?

A transformer is an electrical device that changes the voltage of alternating current (AC) without changing its frequency. It operates on the principle of electromagnetic induction.

Principle of a Transformer:

Transformers work on Faraday's Law of Electromagnetic Induction. When an alternating current passes through the primary coil, it creates a changing magnetic field, which induces a voltage in the secondary coil.

Mathematically,

(Vs / Vp) = (Ns / Np)

Where:

- Vs = Secondary voltage

- Vp = Primary voltage

- Ns = Number of turns in the secondary coil

- Np = Number of turns in the primary coil

Read Also: Power in AC Circuit: The Power Factor – Class 12 Physics Notes

Types of Transformers:

Based on Functionality

- Step-Up Transformer: Increases voltage from primary to secondary.

- Step-Down Transformer: Decreases voltage from primary to secondary.

Based on Construction:

- Core-Type Transformer: Windings surround the laminated core.

- Shell-Type Transformer: Core surrounds the windings.

Based on Usage:

- Power Transformers: Used in transmission networks.

- Distribution Transformers: Used in local electricity distribution.

- Instrument Transformers: Includes Current and Potential transformers used for measurement.

Working of a Transformer:

1. AC Input: An alternating current (AC) flows through the primary coil.

2. Magnetic Field Generation: The AC produces a changing magnetic flux in the core.

3. Induced EMF: This varying flux induces a voltage in the secondary coil.

4. AC Output: The secondary coil delivers AC output, which can be stepped up or down depending on the coil turns.

Transformer Efficiency and Losses:

Efficiency Formula

Efficiency (η) = (P_out / P_in) × 100

Transformer Losses:

1. Copper Loss: Due to resistance in windings.

2. Iron Loss (Core Loss): Caused by eddy currents and hysteresis.

3. Flux Leakage Loss: Incomplete magnetic linkage.

4. Dielectric Loss: Occurs in insulation material.

Applications of Transformers:

- Power transmission and distribution.

- Voltage regulation in electronic devices.

- Used in welding machines.

- Inverters and power supplies.

- Used in measurement instruments.

Conclusion:

Transformers are fundamental devices in electrical engineering, playing a critical role in efficient power transmission and distribution. Understanding their working principle, types, and applications is essential for Class 12 Physics students. Mastering transformer concepts will aid in solving numerical problems and practical applications in the real world.