Physical Science Chapter 19

Ray Diagram

A diagram that shows how light rays change direction when they strike mirror and pass through lenses

Angle of Incidence

Then angle an incident ray makes with line perpendicular to a surface it strikes

Angle of Reflection

The angle a reflected ray makes with a line perpendicular to a surface it strikes

Plane Mirror

A mirror with a flat surface

Virtual Image

A copy of an object formed at the point from which light appears to be coming

Concave Mirror

A mirror that is curved inward

Focal Point

The point at which light rays parallel to the axis of a mirror or lens meet or appear to meet

Real Image

A copy of an object formed at the point where light rays actually meet

Convex Mirror

A mirror that is curved outwards

Index of Refraction

The ration of the speed of light in a vacuum to the speed of light in a medium

Lens

An object made of anything, transparent material that has one or two curved surfaces that can refract light

Concave Lens

A lens that is curved inward at the center and is thickest at the outside edge

Convex Lens

A lens that is curved outward at the center and is thinnest at the outside edges

Critical Angle

The angle of incidence that produces an angle of refraction equal to 90 degrees

Total Internal Reflection

The complete reflection of a light ray back into its original medium when the angle of incidence is greater than the critical angle of refraction

Telescope

An optical instrument that uses lens (or lenses and mirrors) to collect and focus light from distant objects

Reflecting Telescope

A telescope that uses mirrors and convex lenses to collect and focus light

Refracting Telescope

A  telescope that uses only lenses to collect and focus light

Camera

An optical instrument that records an image of an object

Microscope

An optical instrument that uses lenses to provide enlarged images of very small, near objects

Conea

The transparent outer coating of the eye

Pupil

The opening that allows light to enter the eye

Iris

The colored part at the front of the eye, which expands and contracts to control the amount of light entering the eye

Retina

The inner surface of the back of the  eye containing light-sensitive nerve endings

Rods

Light-sensitive neurons in the retina that detect low-intensity light and distinguish black, white, and gray

Cones

Light-sensitive neurons in the retina that detect color

Nearsightedness

An eye condition in which distant objects are blurry

Farsightedness

An eye condition that causes nearby objects to be blurry

Astigmatism

An eye condition in which objects at any distance appear blurry because of the distorted shape of the cornea

Glaucoma

High pressure in the eyes

Cones

Color

Rod

Brightness

Distance objects

Muscles contract

Lens become thinner

Focus shifted back

Near Objects

Muscles relax

Lens become thicker

Focus shifted forward

Concave Lens

Curves Inward

Diverges light

Virtual

Convex Lens

Curves Outwards

Converges Light

Both

Nearsightness

Far objects blurry

eye to long

Lens to thick

concave lens

Farsightedness

Near objects blurry

eye shape to short

lens to thin

convex lens

Virtual Images

Image behind mirror

right side up

converging rays

plane

Real Images

In front of mirror

upside down

diverging rays

Concave

Behind Focal Point

Real

Upside down

Smaller

Front of or at Focal Point

Virtual Image

Right side up

Larger

Hyperopia

Farsightedness

Near objects appear blurry

Conjunctivitis

Pink Eye

Astigmatism

It is Hereditary (Genetics)

Color Blindness

Mainly affects men

Red, Green & Blue is most affected

Keratoconus

Corina bulges out & Thins

Cataracts

Surgery to replace your cloudy lens

Amblyopia

Lazy Eye

Glaucoma

Caused by damage to the Optic Nerve

Presbyopia

Comes with old age

Myopia

Nearsightedness (trouble seeing far)

Lens

Located directly behind the iris

allows eye to focus on objects at varying distances

Cone

Photo-receptor in the retina

responsible for vision at high levels of light

helps to see color

Pupil

part of the ye that lets light in

black circular opening in the iris

Optic Nerve

Send signals from the retina to the brain

Bundle of more than 1 million nerve fibers

Retina

located on the back of the eye

Light sensitive nerves that transfer the energy of light waves to nerve impulses

Iris

colored part of the eye

controls amount of light that enters the eye

Rod

Responsible for vision at low light levels

do not help with seeing colors

Photo-receptor in the retina

Sight

The signal your brain interprets form the Optic Nerve

One of the five senses

Cornea

transparent layer of the eye

where light waves first enter and pass through

Sclera

Tough protective covering of the eye

the white of your eye