A transformer with a primary voltage of 120V AC and a turns ratio of 5:1 means the primary winding has five times more turns than the secondary. This configuration results in a secondary voltage of 24V when 120V is applied to the primary. If the transformer is connected in reverse, applying 120V to the secondary could yield 600V on the primary. However, the primary winding must have sufficient inductance to prevent excessive current, which could damage the transformer. For small transformers, a guideline is to have about five turns of wire for each volt applied.