What side of the transformer is connected to the power source?

The primary coil of a transformer is the part that is connected to the power source. This coil receives electrical energy from the source and generates a magnetic field in the transformer. The purpose of this magnetic field is to induce a voltage in the secondary coil, which is responsible for delivering the transformed voltage output to the load.

When electrical current passes through the primary coil, it creates a magnetic field that passes through the transformer core and intersects with the secondary coil. The relationship between the number of turns in the primary coil and the secondary coil determines whether the transformer steps up or steps down the voltage. However, it is essential to recognize that the primary coil is specifically designed to be the input side of the transformer, where the original electrical energy enters the system.