Question

A transformer:
(A) transforms energy
(B) transforms frequency
(C) transforms voltage
(D) None

Answer 1

A transformer is a device that transfers electrical energy from one electrical circuit to another electrical circuit through mutual electromagnetic induction. There is not any change in frequency when a transformer comes into work. There are some current transformers too.

Complete step-by-step solution:
Transformers are devices that transfer electrical energy from one circuit to another through the property of mutual induction. They actually transform voltage.
The main reason for using transformers is to make power of one voltage level into power of another voltage level. It is easier to send high voltage at long distances but on the other hand not easier and safer to use at home or office. Whereas less voltage is easier and safer to use in the office or home but cannot be sent to long distances. So, transformers are used to increase or decrease alternating current (AC) voltage in circuits. The transformer is usually built with two coils around the same core. The primary coil or input coil is connected to the supply-side while the secondary coil supplies power to load. The second one is called the output coil. Energy is transferred from the primary coil to the secondary coil by the principle of mutual induction. In power grids, many transformers are used. These are networks for delivering electricity from the generator and to the user.

Additional information:
The transformers used in our neighborhood, on electricity poles, or the ones connected to underground wires, usually transform high voltage of $7200{\text{ }}volts$ to $220 - 240{\text{ }}volts$ of electricity to power lights and appliances in homes and other buildings or purpose.
So, it is concluded that transformer transforms voltage and hence option (C) is correct.

Note: It must be noted that the frequency also remains the same during the working of a transformer. Electrical energy is not transformed during the working of a transformer. Transformers are even classified into types such as Step-in transformers where the voltage in the secondary coil increases while in step-down transformers the voltage decreases.