Principle of the working of a transformer is based on which of the following laws?

Explanation:

Principle of the Working of a Transformer

Definition: A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Transformers are used to increase or decrease the alternating voltages in electric power applications.

Working Principle: The working principle of a transformer is based on Faraday's Law of Electromagnetic Induction. Faraday's law states that a change in the magnetic field within a closed loop induces an electromotive force (EMF) in the wire that forms the loop.

In a transformer, when an alternating current (AC) flows through the primary coil, it creates a varying magnetic field around the coil. This varying magnetic field induces a varying magnetic flux in the core of the transformer, which in turn induces an electromotive force (EMF) in the secondary coil. The voltage induced in the secondary coil depends on the turns ratio of the transformer.

Faraday's Law of Electromagnetic Induction: The law can be mathematically expressed as:

EMF = -N × (dΦ/dt)

Where:

• EMF is the induced electromotive force in volts.
• N is the number of turns in the coil.
• dΦ/dt is the rate of change of magnetic flux in the coil.

Construction of a Transformer: A transformer consists of three main parts:

• Primary Coil: This is the coil that receives the input AC voltage.
• Secondary Coil: This is the coil that delivers the output AC voltage.
• Core: The core is made of ferromagnetic material (usually laminated iron) to provide a path for the magnetic flux.

Operation of a Transformer:

1. When an AC voltage is applied to the primary coil, an alternating current flows through it.

2. This alternating current creates an alternating magnetic field in the core of the transformer.

3. The alternating magnetic field induces a varying magnetic flux in the core.

4. According to Faraday's law, the varying magnetic flux induces an electromotive force (EMF) in the secondary coil.

5. The voltage induced in the secondary coil depends on the number of turns in the secondary coil relative to the number of turns in the primary coil (turns ratio).

6. The relationship between the primary voltage (V_p), secondary voltage (V_s), primary turns (N_p), and secondary turns (N_s) is given by the formula:

V_p / V_s = N_p / N_s

Advantages:

• Efficient transfer of electrical energy between circuits.
• Ability to step up or step down voltage levels as needed.
• Isolation between primary and secondary circuits for safety.

Disadvantages:

• Limited to AC applications.
• Losses due to resistance in the coils and hysteresis in the core.
• Requires careful design to minimize losses and maximize efficiency.

Applications: Transformers are widely used in various applications, including power distribution, voltage regulation, impedance matching, and isolation in electronic circuits.

Correct Option Analysis:

The correct option is:

Option 1: Faraday's law

This option correctly identifies the principle on which a transformer operates. Faraday's law of electromagnetic induction explains how a changing magnetic field within a closed loop induces an electromotive force (EMF) in the loop. This principle is fundamental to the operation of transformers, where the alternating current in the primary coil induces a voltage in the secondary coil through a varying magnetic field.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 2: Ohm's law

Ohm's law describes the relationship between voltage, current, and resistance in an electrical circuit. It states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. While Ohm's law is fundamental to understanding electrical circuits, it does not explain the working principle of a transformer.

Option 3: Kirchhoff's law

Kirchhoff's laws consist of two rules: Kirchhoff's current law (KCL) and Kirchhoff's voltage law (KVL). KCL states that the total current entering a junction in a circuit equals the total current leaving the junction. KVL states that the sum of the electrical potential differences around any closed network is zero. These laws are essential for analyzing electrical circuits but do not directly relate to the working principle of a transformer.

Option 4: Fleming's rule

Fleming's rules, including Fleming's right-hand rule and Fleming's left-hand rule, are used to determine the direction of induced current and force in electric motors and generators. Fleming's right-hand rule is used for generators, and Fleming's left-hand rule is used for motors. While these rules are important in the context of electromagnetic induction, they are not specifically used to describe the principle of operation of transformers.

Conclusion:

Understanding the principle of operation of a transformer is crucial for correctly identifying its working mechanism. The correct principle, as explained, is based on Faraday's law of electromagnetic induction. This law describes how a changing magnetic field induces an electromotive force (EMF) in a coil, which is the fundamental concept behind the operation of transformers. Other laws and rules, such as Ohm's law, Kirchhoff's laws, and Fleming's rules, are essential in their respective contexts but do not directly explain the working principle of transformers.