Materials with high refractive indices include diamonds, with a refractive index of around 2.42, and crown glass, typically used in lenses, with an index of about 1.52. These materials slow down the speed of light significantly when it enters them from air or another less dense medium. The substantial decrease in speed is accompanied by a pronounced bending of the light ray towards the normal, leading to a small angle of refraction. This pronounced bending effect is what gives diamonds their characteristic sparkle, as light is not only slowed but also refracted and internally reflected multiple times inside the stone, accentuating its brilliance.

Total internal reflection in optical fibres ensures that light signals are contained within the core of the fibre and do not escape, leading to minimal loss of signal strength over long distances. The core of the fibre is made of a material with a higher refractive index than the surrounding cladding. This difference in refractive indices ensures that light entering the fibre at a certain angle will be totally internally reflected. As a result, the light signal can travel long distances with minimal attenuation, maintaining the quality and integrity of the transmitted information. This principle underpins the efficiency of optical fibre communications globally.

Snell’s Law might not be accurately applied in scenarios involving wavelengths of light comparable to or smaller than the atomic scale of materials, as in the case of X-rays. Here, wave behaviours are influenced by atomic and molecular structures, leading to phenomena like diffraction and scattering. Additionally, when light encounters materials with complex refractive indices, involving absorption coefficients, the application of Snell’s Law becomes more nuanced. In essence, while Snell’s Law provides a foundational understanding of refraction, certain scenarios and materials necessitate a more complex, multifaceted approach to predict light behaviour accurately.

The colour of light, determined by its wavelength, indeed impacts the angle of refraction. This is due to the fact that the refractive index of a medium can vary with the wavelength of light, a phenomenon known as dispersion. Different colours of light (or different wavelengths) will be refracted by different amounts. This is precisely why a prism can separate white light into its constituent colours, creating a spectrum. Each colour of light has a slightly different speed in the glass of the prism, leading to varying angles of refraction and the separation of colours.

Yes, Snell's Law can be applied to any type of wave, including sound and water waves, not just light. The law describes the relationship between the angles of incidence and refraction when a wave passes from one medium to another with a change in wave speed. For sound waves, this can be observed when sound travels through air and enters water or another medium, leading to a change in the wave’s speed and direction. The principles remain consistent; the refractive index and wave speed in the respective media are used to calculate the angles, ensuring Snell’s Law is a universal principle applicable across various types of waves.