**Category:** Electromagnetism  
**Subtype:** Transformers  
**Problem Description:** This problem involves a transformer with an unknown configuration of primary and secondary coils. The task is to determine the turns ratio \( k \) of the transformer based on the measured voltages when connected to an AC voltage source. The first measurement yields a voltage of 160 V, and the second measurement yields 10 V. The goal is to find the value of \( k \) from the given options.