The Human Eye
It is a natural optical instrument which is used to see the objects by human beings. It is like a camera which has a lens and screen system.
The various parts of eye and their functions :
Retina
It is a light sensitive screen inside the eye on which image is formed. It contains rods and cones.
Cornea
It is a thin membrane which covers the eye trail. It acts like a lens which refracts the light entering the eye.
Aqueous humour
It is fluid which fills the space between cornea and eye lens.
Eye lens
It is a convex lens made of transparent and flexible jelly like material. Its curvature can be adjusted with the help of ciliary muscles.
Pupil
It is a hole in the middle of iris through which light enters the eye.
Source: safalta.com
It appears black because light falling on it goes into the eye and does not come back.Ciliary muscles
These are the muscles which are attached to eye lens and can modify the shape of eye lens which leads to the variation in focal lengths.
Iris
It controls the amount of light entering the eye by changing the size of the pupil.
Optical nerve
These are the nerves which take the image to the brain in the form of electrical signals.
Persistence of Vision
It is the time for which the sensation of an object continue in the eye. It is about 1/16th of a second.
Power of Accommodation
The ability of the eye lens to adjust its focal length accordingly as the distances is called power of accommodation.
Colour Blindness
A person having defective cone cells is not able to distinguish between the different colours. This defect is known as Colour Blindness.
The topics discussed in this chapter are as follows:
- Structure of a Human Eye
- Defects of a Human Eye
- Tyndall Effect
- Types of Light
- Dispersion of Light
Students can view and download the chapter from the link given below.
Click here to get the complete chapter
NCERT Solutions for Chapter 11: The Human Eye and the Colourful World
Also Check
Chapter 1: Chemical Reactions and Equations
Chapter 2: Acids, Bases and Salts
Chapter 3: Metals and Non-Metals
Chapter 4: Carbon and its compounds
Chapter 5: Periodic Classification of Elements
Chapter 6: Life Processes
Chapter 7: Control and Coordination
Chapter 8: How do organisms reproduce?
Chapter 9: Heredity and Evolution
Chapter 10: Light - Reflection and Refraction
Chapter 12: Electricity
Chapter 13: Magnetic Effects of Electric Current
Chapter 14: Sources of Energy
Chapter 15: Our Environment
Chapter 16: Sustainable Management of Natural Resources
Check out Frequently Asked Questions (FAQs) for Chapter 11: The Human Eye and the Colourful World
What is short sight? How can it be corrected?
A person having a myopic eye used the concave lens of focal length 50cm. What is the power of the lens?
P = 1/50 = 0.02 dioptre.
