Class 10 Science - WEST-BENGAL
Human Eye and Colourful World
The chapter 'Human Eye and Colourful World' in Class 10 Science explores the wonderful optical instrument inside us and various atmospheric phenomena. Under the WBBSE curriculum, students learn about the structure and functioning of the human eye, common vision defects like myopia and hypermetropia along with their corrections, refraction of light through a glass prism, dispersion of light, and why the sky appears blue or the sun appears red at sunrise. This chapter is highly scoring and carries significant weightage in board exams, frequently featuring both conceptual questions and ray diagrams.
Start Learning FreeKey Concepts
Power of Accommodation
The ability of the human eye lens to adjust its focal length to clearly see objects at varying distances.
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 distant objects are seen clearly but nearby objects are blurred, corrected using a convex lens.
Dispersion of Light
The splitting of white light into its seven constituent colours when passing through a glass prism due to different speeds of different wavelengths.
Atmospheric Refraction
The bending of light rays as they pass through layers of air with varying density, causing phenomena like twinkling of stars and advanced sunrise.
Important Formulas
Board Exam Info
In the West Bengal (WBBSE) Class 10 Physical Science board exam, this chapter typically carries around 4 to 6 marks. Common question types include numerical problems on lens power, drawing ray diagrams for eye defect corrections, and conceptual questions on atmospheric refraction and dispersion.
Frequently Asked Questions
Why do stars twinkle while planets do not?
Stars are distant point-source lights whose light undergoes continuous atmospheric refraction, changing its apparent position. Planets act as extended sources of light consisting of multiple point sources, averaging out the twinkling effect.
Which lens is used to correct myopia and why?
A concave lens is used for myopia because it diverges the incoming light rays before they enter the eye, shifting the image back onto the retina.
Why is the danger signal light red?
Red light has the maximum wavelength in the visible spectrum and is scattered the least by air molecules and fog, making it visible from a long distance.
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