Question

The band of the coloured components of a light beam is called its

• A. refraction
• B. dispersion
• C. scattering
• D. spectrum

Hint:

Think of the rainbow as a natural spectrum of sunlight, where water droplets act as prisms to disperse the white sunlight into its constituent colours.

Answer 1

The Correct Option is D

Step 1: Understand the concept of white light and its components.
White light is composed of different colours, each corresponding to a different wavelength. When white light is separated into its constituent colours, a band of these colours is observed. 
Step 2: Analyze the given options.
 

1. Refraction:
   This is the bending of light as it passes from one medium to another with a different refractive index. While refraction can lead to the separation of colours (as in a prism), refraction itself is not the name for the band of colours.
2. Dispersion:
   This is the phenomenon of the splitting of white light into its constituent colours due to the variation of refractive index with wavelength. Dispersion is the process that creates the band of colours.
3. Scattering:
   This is the phenomenon where light is deflected in different directions by particles in a medium. Scattering can affect the colour of light we see (e.g., the blue sky), but it is not the name for the band of separated colours.
4. Spectrum:
   This is the band of colours obtained when white light is dispersed. It shows the component wavelengths of the light beam arranged in order of their wavelengths or frequencies. For visible light, this band consists of colours from violet to red.

Step 3: Identify the term for the band of coloured components of light.
The band of the coloured components of a light beam, obtained through dispersion, is called its spectrum.