Human Eye and Colourful World Test - 5

To an observer on Earth, the stars appear to twinkle because the physical conditions in the earth's atmosphere are not stationary.

When the muscles are relaxed, the lens becomes thin. Thus, its focal length increases.

In early morning or late evening, sun is near the horizon and sunlight covers a longer distance in earth's atmosphere before reaching us. So, most of the blue-violet light is scattered away. It thus gives a reddish appearance to the sun.

The rays of light from upper and lower edges of Sun bend unequally. Due to unequal bending of light, the image of Sun appears oval and larger in size.

Sky looks dark from moon's surface, because there is no atmosphere to scatter sunlight. Since, there is no scattered light to reach our eye on moon, the sky looks dark (black) instead of blue.

The rod-shaped cells present in the retina are sensitive to dim light.

The human eye forms the image of an object at its retina. Retina acts as a screen for forming the image.

White light bends towards the normal when it passes from air to glass medium, that is, rarer to denser medium.

The cold air layers of the atmosphere behave as an optically denser medium for the light rays whereas warmer air layer acts as the rarer medium for the light rays.