Question

The refractive index of a given piece of transparent quartz is the greatest for:
A) Red light
B) Violet light
C) Green light
D) Yellow light

Answer 1

The refractive index of the material is the ratio of the speed of the light in air and the speed of light in the material. As this is the ratio of the same quantity it is dimensionless. The wavelength of light and the material of the substance is responsible for the refractive index of the material.

Complete answer:
The refractive index is dependent on the wavelength of the light. It determines the bending of the light or the deflection of the light from its path.
Write the formula for the refractive index of the material as shown below.
$\mu = \dfrac{c}{v}$
Where, c is the speed of the light in the air and v is the speed of the light in the medium.

The refractive index of the material is inversely proportional to the wavelength of the light. As the wavelength of the light increases, the refractive index of the material decreases. As the wavelength of the light decreases, the refractive index of the light increases.

The violet colour of the light has minimum wavelength in the visible light spectrum. So, the refractive index is greatest for the violet colour.

So, from the above explanation it is observed that the refractive index of a given piece of transparent quartz is the greatest for violet colour.

Hence, the option B is correct.

Note:
The wavelength of the visible spectrum is 400 nm to 700 nm. The red colour light has maximum wavelength and the violet colour light has minimum wavelength. The formula to find the wavelength is $\lambda = \dfrac{c}{\nu }$.
Here, $\lambda$ is the wavelength and $\nu$ is the frequency.