Lenses Flashcards
A ray coming in parallel…
Emerges through the focal point
A ray coming through the focal point…
Emerges parallel
A ray passing throught the optic centre…
Continues on the same path
An object outside 2F is…
Real, inverted and diminished
An object at 2F is…
Real, inverted and same size
An object between 2F and F is…
Real, inverted and magnified
An object at F is…
At infinity and has no image
An object inside F is…
Virtual, upright and magnified
What are some uses of a convex lens?
Magnifying glass, telescope, binoculars and glasses
What kind of image is formed in a concave lens?
Virtual, upright and diminished
What are some uses of concave lenses?
Telescopes, camera lenses, door peepholes and glasses
What is the power of a lens?
It’s ability to converge or diverge light rays
(Concave) A ray coming in parallel…
Emerges as if coming through the focal point on the same side
What does the cornea do?
It protects the eye and aids in refraction
What is aqueous humour?
It is the clear, watery fluid between the cornea and the lens. It protects and nourishes the lens and enhances refraction.
What does the iris do?
It controls the amount of light entering the eye
What is the pupil?
It is the hole through the iris
What does the lens do?
The lens is connected to the ciliary muscles that change its shape and the power of accommodation
What is vitreous humour?
It is the colourless, transparent gel that gives the eyeball its shape. It aids refraction and the convergence of light entering the eye.
What is the retina?
It is the light sensitive part of the eye that respond to different colours and light intensity
What is the blind spot?
The area that connects to the optic nerve, it has no photoreceptors
Explain myopia.
Also known as short sightedness, the image falls short of the retina. It is corrected with a concave lens.
Explain hyperopia.
Also known as long sightedness, the image falls beyond the retina. It is corrected with a convex lens.
What is accommodation?
It enables the eye to focus on near or far objects. If the lens is fattened, it can focus on near objects. If the lens is stretched thin, it can focus on far objects.
