Science Quest for refraction, the human eye, and

Science Quest Refraction etc

Lens

Transparent object with at least one curved side that refracts light

Types of Lenses

There are 3 types of lenses plane, concave, and convex which manipulate light differently.

2 types of refractions in lenses

Air into glass, glass into air

Where does the light refract in the lenses?

Vertical axis

Converging/convex

lenses bend light rays inward, focusing them to a focal point and creates real images

Diverging/Concave

lenses bend light rays outward, causing them to diverge and create virtual images.

Refraction

Light bending as it passes through multiple mediums

Where does light refract?

At the boundaries of objects

Why does light refract?

Change in the speed of light

What happens when the speed of light decreases?

The density increases

When light enters a denser medium

Light will bend toward the normal

Index of refraction

amount a transparent medium decreases the speed of light

Index of refraction formula n=c/v

speed of light in a vacuum/the speed of light in the medium.

Total Internal Reflection

High-Low refractive index, as the incidence angle increases so does the refracted angle and the incident is reflected back in the medium

Critical Angle

Refracted ray follows along surface of dense medium

What happens if the incident ray is increased beyond the critical angle

The light is not refracted, it is reflected back in the medium

Cornea

Transparent, round, in front of eye, directs light onto the eye and focuses it on the retina

Iris

Coloured part of the eye, muscle that controls amount of light entering the eye

Pupil

Black hole in iris, light enters, size is controlled by iris muscles

Lens

Works with cornea to focus light on retina, fine tunes focusing of light, behind iris

Retina

light forms an inverted image, retina detects light and sends electrical & chemical signals for our brains to perceive, has light sensitive cells

Optic Nerve

transmits signals from retina to brain, brain forms image upright

Whats the structures light passes through?

Cornea, pupil, lens retina, optic nerve

How do we see?

Light rays enter the eye, light rays are refracted as they pass the cornea and lens, light is focused on retina

Blind spot

no light detecting cells where the retina connects with the optic nerve

Specialized Cells

allows us to detect colour and movement (cones and rods in retina)

Cones

Used for colour vision by detecting wavelengths of light, red, green, blue, we can see colours when they are stimulated

Rods

Sensitive to changes in light, shape, and movement, not for detecting colour

What do dogs see?

Only 2 types of cones and less than humans

What do birds and butterflies see?

4 different cones,can see more wavelengths than humans, detect light in UV spectrum

Colour blindness

Inability to distinguish between different colours, occurs when cone cells are absent, damaged, or malfunctioning, difficulty seeing red, green, blue or multiple

Myopia

Nearsighted, inability to see far away, light focuses in front of the retina

Hyperopia

Farsighted, Inability to see close by, focuses behind retina

Presbyopia

Aging of the eye, can’t see nearby

Astigmatism

Can’t see close or far, everything blurred, multiple focus points, improper curvature

2 types of Diverging/Concave?

Camera and Glasses for nearsight

2 types of converging/ convex?

Magnifying glass, telescope,microscope