Class 10 Science - KARNATAKA
Human Eye and Colourful World
The chapter 'Human Eye and Colourful World' explores the wonderful optical instrument inside our body and the mesmerizing phenomena of light in nature. Students learn about the structure and functioning of the human eye, power of accommodation, and common vision defects like myopia, hypermetropia, and presbyopia along with their corrections. It also explains atmospheric refraction phenomena such as the twinkling of stars, advanced sunrise, delayed sunset, and the dispersion of white light through a prism resulting in rainbows, as well as the scattering of light responsible for the blue color of the sky and red appearance of the sun during sunrise and sunset. This chapter is highly scoring and important for the Karnataka SSLC board exams.
Start Learning FreeKey Concepts
Power of Accommodation
The ability of the eye lens to adjust its focal length to clearly see objects at varying distances is called accommodation.
Myopia (Near-sightedness)
A vision defect where a person can see nearby objects clearly but distant objects appear blurred, 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 Light
The splitting of white light into its component seven colors when passing through a glass prism due to different speeds of light rays.
Atmospheric Refraction
The refraction of light by the earth's atmosphere due to varying optical densities of air layers, causing twinkling of stars and advanced sunrise.
Tyndall Effect
The scattering of a beam of light by colloidal particles in a medium, making the path of the light beam visible.
Important Formulas
Board Exam Info
In the Karnataka SSLC (KSEEB) Science examination, this chapter typically carries around 4 to 6 marks. Common question types include diagram-based questions (human eye structure, correction of myopia and hypermetropia, refraction through a glass prism), conceptual reasoning questions (why stars twinkle, why the sky is blue), and numerical problems based on the power of a lens.
Frequently Asked Questions
Why do stars twinkle while planets do not?
Stars are distant point-sources of light. Their light undergoes continuous atmospheric refraction, causing the apparent position and brightness to fluctuate, making them twinkle. Planets are larger, closer collections of point-sources whose total variation averages out to zero, so they do not twinkle.
Why is the danger signal light red in colour?
Red light has the maximum wavelength in the visible spectrum. Therefore, it is scattered the least by air molecules and smoke, allowing it to travel the longest distances and remain visible clearly through fog and smoke.
What causes dispersion of white light through a glass prism?
Different colours of white light travel at different speeds through the glass prism and bend at different angles (deviation), causing them to split into a spectrum of seven constituent colours.
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