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Answers
A.17) An instrument which works from three plane mirrors to form beautiful patterns is kaleidoscope. Explanation: When three mirrors are inclined at an angle, then multiple images are formed in the mirror.
A.18) Kaleidoscope is an optical toy consisting of two mirrors at a particular angle. Some common uses of the kaleidoscope are: Kaleidoscope produces beautiful patterns that are used by fashion designers. A kaleidoscope is used as a toy for entertainment.
A.19) A Glass Prism. It is a device used to split white light into seven colors. It has 2 triangular ends and 3 rectangular sides which help in splitting the white ray of light into a band of 7 colors, also known as spectrum.
A.20) Upon passage through the prism, the white light is separated into its component colors - red, orange, yellow, green, blue and violet. The separation of visible light into its different colors is known as dispersion.
A.21) When white light is passed through a glass prism it splits into its spectrum of colours (in order violet, indigo, blue, green, yellow, orange and red) and this process of white light splitting into its constituent colours is termed as dispersion.
A.22) Rainbow is a natural phenomenon showing dispersion of light.
A.23) The lens present in a human eye is a convex lens. We humans can see different colours or objects. We can see these things because the light from the visible rage of the electromagnetic spectrum, emitted by the objects enters our eyes, passing through a lens and then falls on the retina inside our eyes.
A.24) The phenomenon which enables us to see movies in a cinema hall is known as Persistence of Vision.
A.25) In dim light, your pupil expands to allow more light to enter your eye. In bright light, it contracts. ... More light creates more impulses, causing the muscles to close the pupil. Part of the optic nerve from one eye crosses over and couples to the muscles that control the pupil size of the other eye.
Section-B
A.26) When the earth faces the sun during its rotation, the energy from the sun gives us light and heat. ... The MoonThe moon has an orbit around the earth and we can see it at night because of the reflection of the sun's rays and energy that bounce back to the earth. This is what gives the moon the brilliant white glow.
A.27) The reflection of light can be roughly categorized into two types of reflection. Specular reflection is defined as light reflected from a smooth surface at a definite angle, whereas diffuse reflection is produced by rough surfaces that tend to reflect light in all directions
A.28) full form of 'i' is angle of incidence and of 'r' is angle of reflection. Reflection involves a change in direction of the light ray. ... The angle of incidence is the angle between this normal and the incident ray; the angle of reflection is the angle between this normal and the reflected ray. According to the law of reflection, the angle of incidence equals the angle of reflection.
A.29) Infinite images are formed when two plane mirrors are placed parallel to each other, irrespective of the distance.
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