The source side of a transformer is known as _________

• A. Primary
• B. Secondary
• C. Load
• D. Output

Answer: (A)

The main idea being tested is naming the winding that connects to the power source. The winding connected to the source is the primary winding, the input side of a transformer. It receives the source voltage and current and creates a changing magnetic flux in the core that links to the other winding. The secondary winding is the output side, delivering the transformed voltage to the load. The terms load and output describe what sits on the other side of the transformer, not the source side. In an ideal sense, power in roughly equals power out, with losses accounted for in real transformers.