An Auto-transformer (which has only one winding) may be used as a ______ .

• A. None of these
• B. Both Step-Up and Step-Down transformer
• C. Step-Down Transformer
• D. Step-Up Transformer

Answer: (B)

Step up transformer increases voltage level (decreases secondary current).
Step down transformer decreases voltage level (increases secondary current).

In normal operation of transformer power, flux and frequency remain same (or almost same) at input and output.