Chapter 4 | Lenses Flashcards
How does light react with lenses?
Light will pass through transparent mediums (the lens) that alter the ray.
There are two (2) types of Lenses, what are they and name one specific characteristic they share.
- They have at least one curved side
- Converging
- Diverging
What are the three types of converging lenses?
-Biconvex Lens
-Plano Convex Lens
-Meniscus
The rays converge after refracting!
What are the three types of diverging lenses?
-Bio Concave
-Plano Concave
-Meniscus
Rays spread apart after refracting!
What do lenses have to do with our eyes?
The light rays that may or may not form images correctly in our eyes. (The Vitreous Humor in front of the Retina)
How do images form on our retina?
They form upside down, but the image goes through the optic nerve to the brain which turns it right-side up.
The Focal Point of Converging Lenses is when?
It’s when the real point where the refracted rays meet when incident rays run parallel.
Give some information on images formed by converging lenses.
There are three rays.
1. Ray 1: Travels parallel to Principal Axis
2. Ray 2: Straight through optical centre
3. Ray 3: Travels through secondary Focal Point (F’) then parallel to Principal Axis
But only two (2) rays are needed to determine the location of the image.
The Focal Point of a Diverging Le s is when?
It is when the virtual point from which the refracted rays appear to emanate from when the incident rays are parallel.
(The Focal point is before the lens)
Give some information on images produced by a diverging lens.
There are three rays
- Ray 1: Parallel to Principal Axis
- Ray 2: Goes through Optical Center. Not deviated. (Doesn’t change direction)
- Ray 3: Goes towards secondary F’ (Focal Point) refracted parallel to Principal Axis
* See Diagram*
The image formed by a diverging lens is?
It is always the same irrespective of the position of the object.
What are the three vision disorders?
- Myopia
- Near-sighted vision
- the image forms in from of the retina, so you can only see close up.
- Faraway objects are blurry - Hyperopia
- Far-sighted vision
- You can only see from a distance
- Close objects are out of focus - Astigmatism
- Everything is blurry no matter what - Presbyopia
- Lens get tired and you can’t focus your eyes
- Need reading glasses
What corrects Myopia?
A diverging lens does, because the light rays diverge more the the image forms farther than it usually would, so right on the retina.
What corrects Hyperopia?
A converging lens does, usually the focal point is after the retina, but with the converging lens, the light rays converge the rays right on the retina so someone far-sighted can see everything well.
