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The subsection “Colourful World and Human Eye” explains the details of the anatomy and physiology of the eye, its parts, and some interesting phenomena related to light and color vision. Other concepts covered include and are not limited to the refractive index of different substances, and dispersion and scattering of light which account for phenomena such as the production of a rainbow, the blue appearance of the sky, and the refraction of light by the Earth's atmosphere. This part is important to master because it forms the basics of higher concepts in optics, which is crucial in the future.
Given below are downloadable Class 10 Human Eye Notes in PDF format. Click, download and enjoy your studying session!
Some of the important Notes from the chapter Human eye and the colourful world of class 10 science have been provided to boost your exam preparation. Here are details notes:
Cornea: It is the eye's outer lens, located at the frontal part. It is a transparent cover of the eye which permits the entering of light, in addition it helps in focusing.
Iris:The colored segment of the eye which adjusts the quantity of light crowning into the eye by modifying the pupil's diameter.
Pupil: it is a part of the eye situated in the center of Iris whose chief function is to provide access to light. It is a muscular aperture and it contracts during the day and opens at nighttime.
Lens: It is a convex organ which can at some point of time shift its curvature becomes easy to focus wherein the light is shone.
Retina: The inner portion of the eye, which is impacted by light, and possesses receptors (rods and cones) which serve the purpose of identifying light and colors.
Optic Nerve: It passes the signals that contain the images from the retina to the brain where they are processed as visuals in a targeted manner.
To focus on an object, ciliary muscles change the curvature of the lens accordingly.
Near Point: it is defined to be the closest distance within which an object can be seen distinctly.
Far Point: it is the distance of the furthest object at which the object can be seen clearly (infinity for a normal eye).
Light Refraction Using A Prism
A prism has the shape of a triangle. The light coming into contact with a prism bends on two occasions when it is entering and when it is leaving.
The variation of the light depends on the nature of the material, the angle of incidence, and the wavelength of this light.
Dispersion of Light and Spectrum Formation
Dispersion occurs when the white light is separated into its component colours because of the different wavelengths being refracted at varying angles.
A spectrum is made up of seven colours which are arranged in the order of increasing wavelengths (Orange, Red, Yellow, Green, Blue, Indigo, and Violet).
The twinkling of stars is attributed to the continuous refraction of starlight because of the different densities of air in the atmosphere.
Apparent shift of the sun - The sun seems to be slightly’ above the horizon because of the atmospheric refraction.
The Tyndall effect describes the scattering of light by very small particles present in a colloid.
Why is the color of the sky blue? Blue light has a shorter wavelength than red and therefore gets scattered more.
Why are the sunrises and sunsets red? The light has to travel a longer distance during sunsets and sunrises which make the shorter wavelengths of light get scattered while leaving red as the dominant color.
Given below are important questions which are popular in the exam papers. Go through them and study like a pro, what say?
Question 1: Describe the anatomy and physiology of the human eye.
Answer:
The Human Eye Structure:
The human eye allows an individual to see and comprehend their surroundings and is considered as one of the wonders of nature. Its parts are as below:
Cornea: It is the transparent surface layer and the most front part of the eye which serves as a lens that focuses light to the eye.
Iris: Muscles within the colored parts of the eye which serves to control the pupil’s size, thus controlling the amount of light entering the eye.
Pupil: The opening in the iris which can be increased or decreased depending upon the amount of light.
Lens: It is a flexible biconvex structure which changes its shape (accommodation) to focus light on the retina.
Retina: It is the innermost layer and contains photoreceptor cells, rods (dim light) and cones (color).
Optic Nerve: Transfers the signals coming from the retina which has already been captured to the brain and processed to develop images.
Functions of Human Eye:
To perceive light, shapes and colors alongside depth is offered by the eye.
The eye focuses on both nearby and distant objects due to accommodation
To regulate the potential damage from excessive brightness, the pupil is used to control the amount of light entering the eye.
The eye processes all the images and transfers these signals to the brain through the optic nerve.
Question 2: What is the power of accommodation? How does the eye adjust to view distant and near objects?
Answer: The ability to adapt the lenses of the eyes to focus on an object that is either too far or too close is called the power of accommodation. It is performed by ciliary muscles and it controls the shape of the lenses. Adjustment for Near and Distant Objects
Near Objects: The lens thickens as the ciliary muscles contract and enhances the curvature to a certain extent in order to direct the focus at closer objects. Distant Objects: The ciliary muscles relax which flattens the lens and decreases the curvature so that the focus can be directed to objects located far away. For an average human eye, the near point is 25 cm while the far is infinite.
Question 3: How do spectacles aid in myopia and hypermetropia correction?
Answer: Myopia refers to the condition where
the eyeball is overly large or the lens is overly rounded, causing focusing of light in front of the body instead of on the retina.
Blurry distant objects.
Correction: Concave lenses help shift the patient's focusing point backwards by causing divergence of light rays prior to the eye.
Hypermetropia refers to the condition where the eyeball is smaller than average, or the lens is excessively wide, resulting in the concentration of light behind the retina.
Blurred nearby objects.
Correction: Convex lens assist shifts the patient's focal point forwards by converging light rays coming into the eye.
Question 4: What makes a prism split white light into multiple colors?
Answer: The white light consists of different colors such as (VIBGYOR- Violet, Indigo, Blue, Green, Yellow, Orange, and Red) which all have different wavelengths. Refraction occurs when white light enters a triangular prism (which is the bending of light). Because of the difference in wavelength, varying colors are bent differently. For instance, violet bends the most while red bends the least. The dispersion that results from this activity yields a spectrum.
Question 5: Why does an astronaut see a completely dark sky from space even when the sun is out?
Answers: The scattering of sunlight due to air molecules results in Earth’s sky appearing blue. Due to the lack of atmosphere in space, light cannot be scattered which means there is no diffusion of light. This is why the sky appears dark even when the sun is present.
Question 6: Why is the danger signal red instead of blue?
Answer: Red light is prioritized because it is the least scattered color in the visible spectrum. It also has the longest wavelength in comparison to blue. Due to Red’s low scatter and long distance reach, it is highly visible, even in dusty or foggy situations. For maximum signal visibility, red is the preferred color used in warning signs, traffic signals, and danger signals.
Question7: Why do we see a rainbow only after rainfall?
Answer: Dispersion, internal reflection, and refraction of sunlight within a water droplet causes a rainbow. After rainfall, millions of tiny suspended water droplets are scattered in the air like prisms. Once sunlight enters these droplets, it gets bent, divided into multiple colors, internally reflected within the water droplets before exiting. The entire processes gives birth to a colorful circular arc, which can only be viewed with one’s back towards the Sun.
Light and the human eye are two topics students grapples with, and there are errors that tend to come with that understanding. Those errors are a product of lack of clarity of concepts, definitions, or context. The following are the errors that students make in this chapter:
🚫 Mixing Up Vision Defects: A considerable number of pupils confuse myopia (close vision) versus hypermetropia (long distance vision) alongside the lenses that corrects them (concave for myopia and convex for hypermetropia).
🚫 Dispersion Misconception: A number of folks believe dispersion is the same as refraction while in reality, dispersion splits white light into its constituent colors.
🚫 Diagrams of Ray Illustration Errors: Mistakes that come with drawing the incidents or refracted rays for the prisms and lenses result in wrong conclusions about the image formation.
🚫 Misunderstanding Effects of Atmospheric Refraction: The students’ disorientation that causes the combination of the twinkling of stars to be confused with problematical separation of color is another mistake.
🚫 Ignoring Terms and Their Sizes: A lack of an appropriate SI unit, and standard values including the near point of a standard human eye (25 cm) would create wrong responses.
🚫 Omitting Function of Ciliary Muscles: The students typically tend to forget that ciliary muscles, which control the shape of the lens to a pulpit.
Making notes that are fun to look at and do not require spending too much time on are beneficial for students as they will be able to grasp concepts and remember them easily. The following are tips on how to achieve creative and informative notes for this chapter:
Everyday Usage: Relate and rationalize topics such as the color of the sky, traffic light signals and how rainbows are formed with normal day activities.
Every learner should learn how to take notes, as they prove to be beneficial for learning and revising concepts taught. Below are some prominent advantages from making creative and detailed notes:
Human Eye and the Colourful World, deals with some basic aspects of vision and light phenomena. Its concepts are vital not only for achieving success in studies, but also for experiencing the beauty of nature such as a rainbow, blue sky, and sparkling stars.
If accompanied by effective note-making, conceptual clarity, and consistent practice, mastering this chapter can be reasonably achieved by students and put into practice in their everyday life. Happy learning!
Many students wonder about the role of the cornea in vision. It helps in focusing light that enters the eye and also acts as a protective layer.
Students are often curious about the rods and cones, which are special cells in the retina. Rods help with vision in low light, and cones are responsible for color vision and detailed visual clarity in bright light.
This refers to the ability of the eye’s lens to change shape in order to focus on objects at different distances. It’s one of the key topics students search for when learning how the eye adjusts to various focal lengths.
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