Question

The refractive index of diamond is 2.42. What is the meaning of this statement?

Answer 1

Hint: In optics, a material's refractive index is a dimensionless number that defines how quickly light passes through it.
Where c is the speed of light in vacuum and v is the phase velocity of light in the medium, it is defined as \[n = \dfrac{c}{v}\]

Complete step-by-step solution:
When white light is refracted, the refractive index changes with wavelength, causing it to divide into component colours. This is referred to as dispersion. It may be seen in prisms and rainbows, as well as in lenses as chromatic aberration. A complex-valued refractive index can be used to characterise light propagation in absorbing materials. After then, the imaginary component is in charge of attenuation, while the actual component is in charge of refraction. Across the visible spectrum, the refractive index of most materials varies by several percent with wavelength. However, refractive indices for materials are frequently given with a single value for n, which is usually measured at 633 nm.
Diamond has a refractive index of 2.42. When compared to the speed of light in air, the speed of light in a diamond is reduced by a ratio of 2.42.
To put it another way, the speed of light in a diamond is \[\dfrac{1}{{2.42}}\] that of light in vacuum. The high refractive index of diamond indicates that the diamond's speed is low.

Note: The theory of relativity states that no information can move faster than the speed of light in vacuum, but this does not rule out the possibility of a refractive index of less than one. The refractive index is a measurement of light's phase velocity, which does not contain any information. The phase velocity is the rate at which the wave's crests travel, and it can be faster than the speed of light in vacuum, resulting in a refractive index of less than one.