Practice MCQ Questions and answers on Physics-GK

Red colour has the longest wavelength.

Gases and particles in Earth's atmosphere scatter sunlight in all directions. Blue light is scattered more than other colors because it travels as shorter, smaller waves.

During sunrise and sunset, 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 and the sky appear red.

White light is called as white because it consists of seven colors. The sunlight splits into seven colors namely violet, indigo, blue, green, orange, and red. We usually call it as VIBGYOR.

When white light passes through a glass prism we get a spectrum on the other side of the prism. In the emergent beam the ray which is deviated least is the red ray.

Rainbows are produced when sunlight incident on rain drops hanging in the atmosphere is dispersed after suffering refraction and internal reflection.

Red light is used as danger signal because it is having high wavelength, less scattering ,hence can travel larger distances.

When sunlight hits the surface of sea or ocean, some of the light gets reflected back, whereas, most of the longer wavelengths such as red, orange and yellow penetrate sea water and get absorbed by the water molecules. So only the shorter wavelengths of light which contain violet and blue colors are reflected back to reach our eyes. Hence the sea water appears blue.

Gases and particles in Earth's atmosphere scatter sunlight in all directions. Blue light is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.

Indigo is a dye different than any other. It does not require any mordant. Rather it is dyed through a living fermentation process. The process “reduces” the Indigo, changing it from blue to yellow. In this state, it dissolves in an alkaline solution. The fibre is worked in the solution, or “vat”. When brought out to the air, it is a bright green. Slowly the air changes it to the beautiful deep and rich blue of Indigo.