Question

The transformer is used in……..current circuits
A. Alternating
B. Direct
C. no
D. less

Answer 1

A transformer contains two coils, the primary coil and the secondary coil both wound on a soft iron core. If an ac voltage is applied to the primary coil then this will generate a varying magnetic field in the iron core. This may induce an alternating voltage in the secondary coil according to electromagnetic induction.

Complete step-by-step answer :
First of all let us discuss the transformer. A transformer is described as a passive electrical device that can transfer electrical energy from one circuit to another one through the phenomenon of electromagnetic induction. It is most generally used to increase which is called as step up or decrease which is called as step down voltage levels between circuits. The basic principle on which the transformer works is Faraday's Law of Electromagnetic Induction or mutual induction between the two coils. It works on the alternating current only due to an alternating flux needed for mutual induction between the two windings. $kVA$ Is the abbreviation of Kilovolt-Ampere and is the rating generally used to rate a transformer. The size of a transformer is measured by the kVA of the load. In certain circumstances the power required by the load is similar to the rating of the transformer expressed in either $VA$ or $kVA$ . In short, the transformer is used in alternating current circuits.
Hence the correct answer is option A.

Note : Transformers will not pass direct current and can be used to measure the DC voltage out of a signal while keeping the part that varies. In the electrical grid transformers are key to varying the voltages to decrease how much energy is lost in electrical transmission.