Human Eye and Its Parts

The human eye is the sense organ that helps us to see.

The human eyes are located in eye sockets within the skull.

The average diameter of the human eye is 2.3 cm.

<p>Skin</p> Signup and view all the answers

<p>The cornea is the outermost, transparent part of the eye that helps refract light.</p> Signup and view all the answers

<p>The pupil is the central aperture in the iris that allows light to enter the eye.</p> Signup and view all the answers

<p>Ciliary muscles help modify the shape of the lens to focus on objects at different distances.</p> Signup and view all the answers

<p>The optic nerve transmits visual information from the retina to the brain.</p> Signup and view all the answers

<p>The blind spot is the point where the optic nerve exits the eye. It is a blind spot because there are no light-sensitive cells at this point, resulting in a lack of vision.</p> Signup and view all the answers

<p>The aqueous humor, a transparent fluid, helps focus light onto the retina and provides nutrients to the eye.</p> Signup and view all the answers

<p>The far point of the eye is the maximum distance at which an object can be seen clearly without any strain.</p> Signup and view all the answers

<p>Accommodation is the process by which the ciliary muscles change the focal length of the eye lens so that clear images are formed on the retina, regardless of the object's distance.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>The range of human vision is from 25 centimeters to infinity.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Myopia, or nearsightedness, is a refractive error where distant objects appear blurry. It can be caused by excessive curvature of the eye lens or stretching of the eyeball.</p> Signup and view all the answers

<p>Myopia is corrected using concave lenses that diverge light rays before they enter the eye, allowing them to focus properly on the retina.</p> Signup and view all the answers

<p>Hypermetropia, or farsightedness, is a refractive error where nearby objects appear blurry. It can be caused by a short focal length of the eye lens or a small eyeball.</p> Signup and view all the answers

<p>Hypermetropia is corrected using convex lenses that converge light rays before they enter the eye, allowing them to focus properly on the retina.</p> Signup and view all the answers

<p>Having eyes positioned in front of the face provides a wider field of view and allows for three-dimensional perception, giving us a better sense of depth.</p> Signup and view all the answers

<p>Dispersion of light is the splitting of white light into its different color components due to their varying bending ability.</p> Signup and view all the answers

<p>Total internal reflection occurs when light travels from a denser medium to a rarer medium with an angle of incidence greater than the critical angle, causing the light to reflect back into the denser medium.</p> Signup and view all the answers

<p>The angle of incidence must be smaller than the critical angle.</p> Signup and view all the answers

<p>Rainbows are formed when sunlight passes through water droplets in the atmosphere. The light undergoes refraction (bending) and internal reflection within the droplets, separating colors and creating a colorful arc.</p> Signup and view all the answers

<p>The sky appears blue because blue light from the sun is scattered more than other colors by tiny atmospheric particles. This scattering, called Rayleigh scattering, makes the blue light visible from all directions.</p> Signup and view all the answers

<p>During sunrise and sunset, the sun's light travels through a greater portion of the atmosphere. This causes shorter wavelengths of light (like blue and green) to be scattered away, leaving the longer wavelengths (like red and orange) to reach our eyes, resulting in a reddish appearance.</p> Signup and view all the answers

<p>Red light has the longest wavelength in the visible spectrum and is scattered the least by the atmosphere. This makes red light visible from a greater distance, making it suitable for warning signals.</p> Signup and view all the answers

<p>Yellow is a highly visible color, especially in daytime, making school buses easily noticeable to other drivers, helping to ensure the safety of children.</p> Signup and view all the answers

<p>Celestial bodies appear slightly raised due to atmospheric refraction. As light from these objects travels through different layers of the atmosphere, it bends, causing the apparent position to differ from the actual position.</p> Signup and view all the answers

<p>The 2-minute difference is attributed to atmospheric refraction. When the sun is near the horizon, its light is bent by the atmosphere, making it appear to rise earlier and set later.</p> Signup and view all the answers

<p>Stars twinkle due to the turbulence in Earth's atmosphere. The light from stars, being very far away, is refracted in different directions as it passes through the turbulent atmosphere. Planets, being closer to Earth, have less light disruption, resulting in a more steady appearance.</p> Signup and view all the answers