Question

Transformer is a device used for

• A. Changing the electrical energy into mechanical energy
• B. Changing the mechanical energy into electrical energy
• C. Changing the voltage from one value to another without change in frequency
• D. Changing the frequency from one value to another without change in voltage

Hint:

Remember the energy conversions for key electrical devices:
• Motor: Electrical \(\rightarrow\) Mechanical
• Generator: Mechanical \(\rightarrow\) Electrical
• Transformer: Electrical \(\rightarrow\) Electrical (at different voltage/current levels) This helps differentiate them easily.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
This question asks for the primary function of a transformer. A transformer is a fundamental component in electrical engineering, especially in power systems.

Step 2: Detailed Explanation:
A transformer is a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. A varying current in one coil of the transformer produces a varying magnetic field, which in turn induces a varying electromotive force (EMF) or "voltage" in a second coil.
The core functions and characteristics of a transformer are:

• Voltage Transformation: Its primary purpose is to "step-up" (increase) or "step-down" (decrease) AC voltages. This is achieved by having different numbers of turns in the primary and secondary coils.

• Constant Frequency: The process of electromagnetic induction does not alter the frequency of the alternating current. The frequency of the output voltage is the same as the frequency of the input voltage (e.g., 50 Hz in India, 60 Hz in the US).

• Power Transfer: Ideally, a transformer transfers power from the primary to the secondary circuit with no loss, so \(P_{in} = P_{out}\) or \(V_p I_p = V_s I_s\). In a step-up transformer, voltage increases while current decreases, and vice versa for a step-down transformer.
Let's analyze the options:
(A) Changing electrical to mechanical energy is the function of an electric motor.
(B) Changing mechanical to electrical energy is the function of a generator or dynamo.
(C) This accurately describes the function of a transformer: it changes voltage levels while keeping the frequency constant.
(D) Devices that change frequency are called frequency converters or cycloconverters. This is not the function of a standard transformer.

Step 3: Final Answer:
A transformer is used for changing the voltage from one value to another without a change in frequency.