Transformer is used to 1. convert low a.c. voltage to high voltage 2. convert high a.c. voltage to low voltage 3. convert direct current to alternating current 4. regulate the fluctuation of voltage

A transformer is a static electrical device that operates on the principle of electromagnetic induction to change alternating current (AC) voltage levels. It is classified into two main types: step-up transformers, which increase low AC voltage to a higher voltage, and step-down transformers, which decrease high AC voltage to a lower voltage. Statement 3 is incorrect because transformers do not convert direct current (DC) to alternating current (AC); that function is performed by an inverter. Furthermore, transformers require a varying magnetic field to function, meaning they do not operate on steady DC. Statement 4 is also incorrect as voltage regulation or stabilization is typically the role of a voltage regulator or stabilizer, not a standard transformer. Therefore, only statements 1 and 2 accurately describe the primary functions of a transformer.

Sources

1. [1] https://en.wikipedia.org/wiki/Transformer
2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > az.r.z. Concentrated Solar Power (CSP) or solar thermal technology. > p. 288