Which of the following statements is true of a step-down transformer but not a step-up transformer?

• A. The transformer increases the voltage from primary to secondary.
• B. The secondary current is lower than the primary current.
• C. The number of turns in the secondary coil is greater than in the primary coil.
• D. The secondary voltage is lower than the primary voltage.

Answer: (D)

Verified step by step guidance

1. Recall the basic function of transformers: they change the voltage and current levels between the primary and secondary coils based on the ratio of the number of turns in each coil.
2. Understand that a step-down transformer decreases voltage from the primary coil to the secondary coil, meaning the secondary voltage is lower than the primary voltage.
3. Recognize that in a step-down transformer, the number of turns in the secondary coil is less than the number of turns in the primary coil, which causes the voltage to decrease.
4. Note that the current behaves inversely to the voltage in transformers, so in a step-down transformer, the secondary current is higher than the primary current.
5. Therefore, the statement 'The secondary voltage is lower than the primary voltage' is true for a step-down transformer but not for a step-up transformer, which increases voltage.