Final answer:
The turn ratio of coils in a transformer with a coefficient of coupling close to unity is determined by the transformer equation, which compares the number of turns in the primary and secondary coils.
Step-by-step explanation:
When the coefficient of coupling between two coils is close to unity, it implies that the coils are almost perfectly magnetically linked. This scenario is often represented in an ideal transformer, where the turn ratio of the coils sets can be determined using the transformer equation which states that the ratio of the secondary to primary voltages in a transformer equals the ratio of the number of turns in their coils.
For the given scenario with two toroidal coils, if the first coil has 1000 turns and the second is wound with 750 turns, the turn ratio would be the number of turns in the secondary coil (750 turns) divided by the number of turns in the primary coil (1000 turns), giving a turn ratio of 0.75:1.