Human Eye and Colourful World Class 10 Notes CBSE Science Chapter 11 [Free PDF Download]

• The front part of the eye is covered with a transparent spherical membrane known as the cornea. Light enters the eye through the cornea. Space present just behind the cornea contains a fluid known as aqueous humour.

• Just behind the cornea is a muscular diaphragm, which is dark coloured and is known as the iris which has a small circular opening in the middle called the pupil. The black colour of the pupil is due to no light being reflected from it. The iris is responsible for controlling the amount of light entering the eye by adjusting the size of the pupil.

• The lens of our eyes is a convex lens made of a transparent jelly-like proteinaceous material. The eye lens is hard in the middle and becomes soft towards the outer edges. The ciliary muscles hold the eye lens in its position. The ciliary muscles are responsible for changing the curvature and focal length of the eye lens.

• The inner back surface of the eyeball is the retina. It is a semi-transparent membrane that is light sensitive and behaves as the screen of a camera. The light-sensitive receptors present in the retina are rods and cone cells. When the light falls on these receptors, they are responsible for sending electrical signals to the brain via the optic nerve. The space between the retina and eye lens is filled with vitreous humour.

• The light coming from an object enters the eye through the cornea and pupil. The eye lens is responsible for converging these light rays to form a real, inverted, and diminished image on the retina. The light-sensitive cell present in the retina gets excited as the light incidents and generates electrical signals. These electric signals are sent to the brain via the optic nerves and the brain interprets these electrical signals in such a manner that we are able to see an image that is erect and is of the same size as that of the object. Accommodation of the eye is said to be the ability of the eye to focus on objects lying at certain distances.

• Whereas the range of vision is the distance between the near point and the far point.

• Colour vision occurs through cone cells of the retina which are excited only in bright light. You cannot differentiate between red, violet, or purple flowers in a garden in moonlight, because of the rod cells' function and not of cone cells.

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Defects of Eye

• Colour blindness or colour vision deficiency is a condition in which a person is unable to distinguish between certain colours. The most common cause could be genetic. Cone cells, which are colour sensitive receptors containing single visual pigments which are selective for red, green, and blue light, are present in the normal human eye. Disturbances in colour vision occur when the amount of pigment per cone is either reduced or are absent.

• Nyctalopia is an inability of a person to see in relatively low light. It is considered a symptom of several eye diseases.  Night blindness could be inborn or can occur due to any injury or malnutrition. Lack of Vitamin A could also play an important role in this. The outer layer of the retina is composed of more rods than cones. The rod cells are responsible for the vision in low light and the reason why the loss of side vision often results in night blindness.

• Cataract is an opacity in the crystalline lens of the eye. In the early stage of age-related cataract, the crystalline lens power can be increased, causing near-sightedness (or myopia) which leads to the gradual yellowing and full opaqueness in the lens which reduces the perception of blue colours. Cataracts develop due to a number of reasons which include long-term exposure to ultraviolet rays, and exposure to radiation is usually due to a result of denaturation of lens proteins.

• Hypermetropia is an eye defect in which a person is incapable of seeing near objects but his distant vision is clear. In a normal eye, the light rays coming from the object fall on the retina but in the case of a hypermetropic eye, these light rays get focused behind the retina.

• Myopia is an eye defect in which a person is not able to see distant objects clearly. Since a person can not see distant objects clearly, this defect is also  known as nearsightedness.

• Astigmatism is the commonly occurring eye defect that results in distorted images since light rays are unable to meet at common focus. Astigmatism may lead to Hypermetropia or Myopia.

• Presbyopia is the condition in which the centre of the eye lens becomes hard making it capable of accommodating near vision. This condition is quite common with person over the age of 50 and even those with myopia.

Human Eye and Colourful World Class 10 Notes: Free PDF Download Contents of Chapter 11 Science Class 10 Notes 

The science Chapter 11 Class 10 notes focus on teaching students more about the complexities of the human eye. The eyes are one of the five sense organs and its function is related to providing visual inputs to the brain. The brain then treads the inputs and forms of images. The whole idea of the Chapter 11 Class 10 Science notes focuses on giving a basic idea of how the eye works and what its structure is like.

Class 10 Science Chapter 11 – Summary

Mentioned below is the short summary of Chapter 11. The detailed explanation of the important concepts is provided in an easy-to-understand way in the revision note of Class 10 Science Chapter 11. Let us quickly look at some of the critical points of Chapter 11.

Structure of Human Eye:The human eye is different from the eye of other species. The human eye is classified as a simple eye structure. There are fluids present in the eye which helps in maintaining its structure and rigidity. The parts of the eye discussed are as follows:

• Cornea: The front part of an eye.

• Iris: The muscles responsible for controlling the eye aperture.

• Lens: It is a convex lens in the case of humans.

• Retina: The inner part of the eye with sensory cells.

• Sclera: Muscular layer of the eye.

• Vitreous Humor: Fluid in the eye.

• Aqueous Humor: Fluid in the eye.

Defects in The Human Eye: As the eye is a complex system of a number of cells and tissues as well as fluids, it is not uncommon for people to encounter defects within the eye. These defects can be noted in a number of individuals and are fairly common. The common defects noted in the human are listed below:

• Myopia: near-sightedness

• Hyperopia: Distant vision is clear but near vision is affected

• Presbyopia: inability to accommodate eye

• Cataracts: Age-related eye defect

• Colour Blindness: Inability to distinguish colours.

Refraction of Light Through a Prism

Different wavelengths of light bend at various angles as it slows and passes through the prism. As a result, light is split into various wavelengths and creates a rainbow of colours. The visible light wavelengths that an item reflects or transmits affect how coloured it appears to the human eye.

Dispersion of White Light by a Glass Prism

White light disperses into its array of colours when it passes through a glass prism, in the following order: violet, indigo, blue, green, yellow, orange, and red. This phenomenon of white light separating into its component colours is known as dispersion.

Atmospheric Refraction

The deflection of sunlight or another electromagnetic wave caused by the earth's atmosphere fluctuation in air density as a function of altitude is known as atmospheric refraction.

Scattering of Light

When light travels through one medium and into another, such as air or a glass of water, some of the light is absorbed by the medium's particles before it radiates in a specific direction. Light scattering is the word used to describe this phenomenon. The size of the dispersed light's particles and its wavelength affect how intense it is. Light scattering is what gives the sky its blue hue and the Sun its reddish hue at sunrise and dusk.

Benefits of  CBSE Class 10 Science Chapter 11 Revision Notes

The following are some of the advantages of using  CBSE Class 10 Science Chapter 11 Notes for preparation.

• Revision notes are curated by experts with a primary focus to cover all the important topics.

• The notes are in a simple, precise, and easy-to-understand format.

• The revision notes contain a list of important diagrams that would help in a better understanding of the concept.

• Concepts are followed by examples for a better understanding of the theories.

Tips to Prepare From CBSE Class 10 Science Chapter 11 Notes

The Class 10th science Chapter 11 notes are the perfect study companion for you. Let us now look at some tips to study from the notes!

• Firstly, it is important to read the NCERT textbooks blindly. The books will give you a basic outline of the topics. Then you must go through the Class 10 Chapter 11 science notes to further improve understanding and increase the chances of students getting higher marks. 

• Look at the model answers provided at the end. 

• Practise the related diagrams to score maximum marks.

This was the complete discussion of the Human Eye and Colourful World Class 10 Notes. We hope to have helped students with their queries. We wish you all the very best for your exams!

Additional Materials Provided by Vedantu:

• NCERT Solutions for Class 10 Science Chapter 11

Chapter wise Revision Notes for CBSE Class 10 Science

• Chapter 1 - Chemical Reactions and Equations Notes

• Chapter 2 - Acids, Bases and Salts Notes

• Chapter 3 - Metals and Non-metals Notes

• Chapter 4 - Carbon and Its Compounds Notes

• Chapter 5 - Periodic Classification of Elements Notes

• Chapter 6 - Life Processes Notes

• Chapter 7 - Control and Coordination Notes

• Chapter 8 - How do Organisms Reproduce Notes

• Chapter 9 - Heredity and Evolution Notes

• Chapter 10 - Light Reflection and Refraction Notes

• Chapter 12 - Electricity Notes

• Chapter 13 - Magnetic Effects of Electric Current Notes

• Chapter 14 - Sources of Energy Notes

• Chapter 15 - Our Environment Notes

• Chapter 16 - Management of Natural Resources Notes