How is the index of refraction (IOR) calculated?

The index of refraction (IOR) is a dimensionless number that indicates how much the speed of light is reduced in a medium compared to its speed in a vacuum. This concept is crucial in optics as it describes how light bends or refracts when it enters a different medium.

The correct method for calculating the index of refraction is indeed to divide the speed of light in a vacuum by the speed of light in the medium (such as optical fiber). This relationship is expressed mathematically as:

IOR = (Speed of light in vacuum) / (Speed of light in the medium)

In the case of option B, it accurately reflects this relationship by focusing on the comparison of the speed of light in a vacuum to its speed in an optical fiber. The index of refraction then indicates how much the light slows down due to the physical properties of the optical medium, which is fundamental in designing lenses, fiber optics, and other optical devices.

The other options do not correctly define the index of refraction. For instance, dividing the speed of sound by the speed of light does not relate to optical properties and reflects different physical phenomena. Likewise, multiplying the speed of light by the wavelength pertains to concepts like energy or angular frequency but does not yield the index