The correct answer is Refractive index.![image](//cdn. Points

• The refractive index of a medium is defined as the ratio of the speed of light in a vacuum to the speed of light in that medium.

• It is a dimensionless quantity and symbolized by "n". The mathematical formula for refractive index is n = c/v, where "c" is the speed of light in a vacuum, and "v" is the speed of light in the medium.

• The refractive index determines how much the path of light is bent or refracted when it enters a different medium.

• A higher refractive index indicates that light travels slower in the medium compared to a vacuum.

• The refractive index is a critical parameter in optics, influencing lenses, prisms, and optical instruments.![image](//cdn. Information**

• Frequency

• Frequency refers to the number of wave cycles that pass a given point per second. It is measured in hertz (Hz).

• It is a fundamental property of waves, including light waves, but it does not define the speed of light in a medium.

• The frequency of light remains constant when it enters a different medium, even though its speed and wavelength may change.

• Wavelength

• Wavelength is the distance between two successive crests or troughs of a wave.

• It is inversely proportional to the frequency of the wave and directly influenced by the speed of the wave in a medium.

• When light enters a medium, its wavelength changes, but the refractive index is determined by the speed, not the wavelength.

• Amplitude

• Amplitude refers to the maximum displacement of a wave from its equilibrium position.

• It is associated with the intensity or brightness of light but does not influence the refractive index of a medium.

• The refractive index depends solely on the speed of light in the medium and not on its amplitude.