Tag: effects of light

Answer is D.

The rainbow is caused by light from the sun (or moon) interacting with raindrops falling from the air. These raindrops are mostly round. A ray of light entering such a droplet is bent (refracted) and decomposed into all possible colors (wavelengths) which the white light consists of. The ray then reflects internally in the droplet, and emerges roughly into the direction it came from when it entered the drop. Since the rays of the different colors all exit at slightly different directions, we see a color band in the sky.
The colors are produced by a phenomenon called dispersion. Dispersion causes white light, which consists of all possible colors to break up into all components, when the light travels from one medium (e.g. air) to another (e.g. water). The different colors of light have all slightly different directions, so if we look in a certain direction in the sky we can see the spectrum.

C. The blue colour of sky is due to scattering of light   = correct statement

The blue colour of sky is due to the scattering of light by small particles of the atmosphere (air molecules) when the light is incident on particles whose size is smaller than the wavelength of light, it is scattered.

According to Rayleigh law, the intensity of scattered light is inversely proportional to the fourth power of wavelength.

Option C is correct answer.

During sunset and sunrise, the rays have to travel a larger part of the atmosphere because they are very close to the horizon. Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun appear red..

Answer is A

Setting sun appears to be red because red light which has greatest wavelength is least scattered and reaches our eyes the most. Other wavelength are scattered to the longest extent. So, reason given is wrong.

Larger particles scatter light at the red end of the spectrum the least as the amount of scattering decreases with increase in wavelength..

Colloidal solution of sodium thiosulphate consists of fine particles that mainly scatters blue light. Hence, it appears blue from the side of the beaker.

Particles smaller than the wavelength of light scatters the light in all directions. In visible spectrum, they scatter violet the most and red the least. However, when the particles are larger than the wavelength of light, then the scattering of all wavelengths occur to same extent.