Topic 4 Flashcards
Lenses
A curved piece of transparent material (typically glass or plastic) which refracts (bends) light.
Convex lens
Causes light to converge (move towards each other)
Real image
Images where light actually converges (Only convex lenses can create real images)
Concave lens
causes light rays to diverge (move away from each other)
Virtual image
An upright image that is achieved where the rays seem to diverge
(Virtual images are primarily formed by concave lenses.)
Nearsightedness
The image is focused in front of the retina, rather than directly on it. Occurs when the physical length of the eye is greater than the optical length.
A nearsighted person sees near objects clearly, while objects in the distance are blurred.
Farsightedness
The visual image is focused behind the retina rather than directly on it
May be caused by the eyeball being too small or the focusing power being too weak.
Is often present from birth, but children can often tolerate moderate amounts without difficulty and most outgrow it
A farsighted person sees faraway objects clearly, while objects that are near are blurred
How does a camera take a picture?
Light is reflected off the object and into the lens of the camera.
Which part(s) in the camera and eye are similar?
Light sensors - retina
Aperture- pupil
Lense(s)- cornea and lens
Diaphragm- iris
Focusing ring - ciliary muscle
Eyelids
- A protective covering for your eyes, shielding them from outside objects and light. They also keep moisture in and help the surface of your eyes stay lubricated.
Sclera
The sclera is the white part of the eye. It provides a protective coating, which covers most of the eye.
Iris
The iris is the colourful part of the eye. It can change in size to control how much light goes through the pupil.
Cornea
The cornea is the clear dome that sits in front of the iris (the coloured part of the eye). It helps your eye focus as light passes through.
Pupil
The pupil looks like a black circle in the centre of the eye but it is really an opening in the iris which lets light enter the eye. The pupil can change in size; it gets smaller in very bright conditions and larger in dark conditions.
The Anterior Chamber
The anterior chamber is the space between the cornea and the iris. This space is filled with a special fluid that helps keep the eye healthy.
The Lens and Ciliary Muscle
After light enters the pupil, it hits the lens. The lens sits behind the iris and is clear. The lens’ job is to focus light rays on the back of the eyeball. The lens is held in place by the ciliary muscle. It can change the shape and thickness of the lens to help you focus on objects that are up close or far away.
When you look at things up close, the lens becomes thicker. When you look at things far away, the lens becomes thinner.
