Step 1: Understanding the Concept:
Magnetic field at centre of a coil \(B = \frac{\mu_0 I}{2R}\). When two coils are perpendicular, resultant field is vector sum.
Step 2: Detailed Explanation:
Let \(B\) be field due to one coil. Since coils are perpendicular, fields are perpendicular to each other.
Resultant field = \(\sqrt{B^2 + B^2} = \sqrt{2}B\).
Ratio of field due to one coil to resultant = \(\frac{B}{\sqrt{2}B} = \frac{1}{\sqrt{2}}\).
Step 3: Final Answer:
Thus, ratio = \(1:\sqrt{2}\).