Science Olympiad Test: Human Eye and Colorful World- 1 - Class 10 MCQ

Here, distance of far point x = 50 cm
As f = – x ∴ f = – 50 cm
Power, P = 100/f  = 100/−50 = – 2 dioptre
Negative sign indicates that the lens used is concave

The human eye lets us see the world by sending impulses to our nervous system. In many ways, it is very similar to other optical devices, including cameras. Your eyes and your brain work together to allow you to see.

Iris is located behind the cornea and is a dark muscular diaphragm that controls the size of the pupil. The pupil regulates and controls the amount of light entering the eye. When bright light falls on the eye the pupil contracts so that less light can enter the eye. However, when dim light falls on the eye the pupil expands so that more light can enter the eye.

Dispersion is the phenomenon of splitting of polychromatic light into its constituent colours. The band of colours obtained on the screen on passing white light through a prism is called a spectrum.

Animation works by using an optical illusion. Film theorists often refer to this illusion of movement as the persistence of vision. The persistence of vision works because the human eye and brain can only process 10 to 12 separate images per second, retaining an image for up to a fifteenth of a second.
Persistence of vision is the eye's ability to keep seeing an image of an object for a fraction of a second after the object has disappeared from view. The principle of persistence of vision is used in making motion pictures and animated cartoons.

The essential condition for Rayleigh scattering is that size of scatterer (x) must be far less than the wavelength of light.

The longest visible wavelength is 800.0Å. It is of red colour.

The sun is visible to us about 2 minutes before the actual sunrise, and about 2 minutes after the actual sunset because of atmospheric refraction.

Rayleigh scattering is the (dominantly) elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. The amount of scattering is inversely proportional to the fourth power of the wavelength.

When a ray of light enters the glass prism it gets deviated two times. First when it enters the glass prism and second when it comes out of the prism. This is because the refracting surfaces of the prism are not parallel to each other. Also, when the ray of light passes through the prism it bends towards its base.