Parts of the Eye
This part of the eye controls the amount of light entering it.
Iris
This function helps us see objects clearly at different distances.
Power of Accomodation
This defect is also known as nearsightedness.
Myopia
This is the bending of light as it passes from one medium to another.
Refraction
A concave lens has a focal length of 50 cm. What is its power?
-2D
This is the clear, dome-shaped surface that covers the front of the eye.
Cornea
The eye forms an image on this light-sensitive layer
Retina
This defect occurs when the eye cannot focus on near objects.
Hypermetropia
This natural phenomenon occurs due to dispersion, refraction, and total internal reflection
Rainbow
A convex lens has a power of +4 D. What is the focal length in meters and cm?
+0.25 m or +25 cm
This part adjusts the shape of the lens for focusing.
Ciliary Muscle
This fluid fills the space between the lens and the retina.
Viterous Humour
This condition makes it difficult to see both near and far objects due to aging.
Presbyopia
This phenomenon causes stars to appear to twinkle
Atmospheric Refraction
A myopic person has a far point of 2 m. What power of lens is required to correct his vision?
- 0.5D
This part sends visual information to the brain.
Optic Nerve
This happens when the eye lens becomes cloudy.
Cataract
This lens is used to correct myopia
Concave
This term describes the splitting of white light into its colors.
Dispersion
A person is prescribed a lens of power +2.5 D. What is the focal length of the lens in centimeters? Also, identify the type of lens.
+40 cm (f = 100/2.5), and it is a convex lens.
Name the part of the eye responsible for maintaining intraocular pressure and describe its role.
Aqueous Humour
The minimum distance at which the eye can focus clearly.
Near Point
How the shape of the eyeball affects vision in myopia and hypermetropia.
In myopia, the eyeball is elongated, causing images to form in front of the retina. In hypermetropia, the eyeball is too short, causing images to form behind the retina.
This phenomenon causes the sky to appear blue.
Scattering of Light
A student uses a lens of focal length –25 cm to correct his vision.
a) What defect does the student have?
b) What is the power of the lens?
c) What is the nature of the lens?
a) Myopia
b) Power = 100/f = 100/(–25) = –4 D
c) Concave lens