Class 10 Science - BIHAR
Human Eye and Colourful World
The chapter 'Human Eye and Colourful World' in Class 10 Science explores the wonderful optical instrument inside us and natural phenomena caused by light. Students learn about the structure and working of the human eye, power of accommodation, and common vision defects like myopia, hypermetropia, and presbyopia along with their corrections using lenses. Furthermore, it delves into atmospheric refraction, explaining why stars twinkle, why the sky appears blue, and why the sun appears red at sunrise and sunset. This chapter is highly scoring and carries significant weight in the Bihar Board (BSEB) matriculation examinations, featuring both conceptual and numerical questions.
Start Learning FreeKey Concepts
Power of Accommodation
The ability of the eye lens to adjust its focal length to clearly see objects situated at various distances.
Myopia (Near-sightedness)
A vision defect where a person can see nearby objects clearly but cannot see distant objects distinctly, corrected using a concave lens.
Hypermetropia (Far-sightedness)
A vision defect where a person can see distant objects clearly but cannot see nearby objects distinctly, corrected using a convex lens.
Dispersion of White Light
The splitting of white light into its seven constituent colors when passing through a glass prism, forming a spectrum.
Atmospheric Refraction
The refraction of light by the earth's atmosphere, which is responsible for phenomena like the twinkling of stars and advanced sunrise.
Scattering of Light (Tyndall Effect)
The phenomenon in which light is deflected in all directions by colloidal particles, explaining why the sky is blue and danger signals are red.
Important Formulas
Board Exam Info
In the Bihar Board (BSEB) Class 10 Science examination, this chapter typically carries around 5 to 8 marks. Questions usually include objective (MCQs), short-answer type questions on eye defects and atmospheric phenomena, and sometimes numerical problems based on lens power or ray diagrams for prism and eye defects.
Frequently Asked Questions
Why do stars twinkle while planets do not?
Stars are distant point-sized sources of light. Their light undergoes continuous atmospheric refraction, causing their apparent position and brightness to flicker (twinkle. Planets are closer, acting as extended sources of light, so the variations average out to zero.
Why is the danger signal light red in color?
Red light has the maximum wavelength in the visible spectrum. Therefore, it is scattered the least by air molecules and smoke, allowing it to be seen from a very long distance through fog and rain.
What causes the rainbow to form in the sky?
A rainbow is a natural spectrum caused by dispersion of sunlight by tiny water droplets present in the atmosphere. These droplets act like small prisms that refract, disperse, and then reflect internally the light.
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