Light

Light

• Photon is a bundle of light related to the amount of energy

• Light travels in straight line paths called light rays

http://www.youtube.com/watch?v=iletCKDCt_0&feature=related

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Reflection of Light

• The bouncing back of light• Regular reflection when

surface is a smooth surface• Diffused reflection when

the surface is irregular

Reflection and Mirrors

• Based on the shape of its surface a mirror is classified as plane, concave, or convex

Concave Mirrors

Good for focusing

Convex Mirror

• Large area of

reflection

• Distorts distance

objects are closer

that they appear

Refracting

• Bending of light due a change in its speed

• Every medium has an index of refraction; comparing its speed with the speed in air

http://www.youtube.com/watch?v=OdcHCRF00jM&feature=related

Mirages

• Refraction of light by the Earth’s atmosphere

Bending and Separating

• Rainbows or through prisms to form spectrum ROYGBIV

• Red has the longest wavelength, so it is bent the least

• Violet has the shortest wavelength, so it is bent the most

Refracting and Lenses

• A lens is any transparent material that refracts light

Convex Lens

• Thicker in the center than at the edges• Bends light rays toward the center

Concave Lens

• Thicker at the ends that the center

• Light rays are bent outward toward the edges

Materials

• Light can be transmitted through a transparent object

• Light can be transmitted with little detail through translucent object

• Light is not transmitted through an opaque object

The Color of Objects

• The color of the object is the color of light reflected from the object to your eye

• All light reflected is white

• All light absorbed is black

Adding Primary Colors of Light

• The primary colors of light are red, blue, and green

How We See

•Light enters the eye through the black opening in the center of your eye.

•It is black because no light is reflected from it.

The Pupil

•The colored area surrounding the pupil.

•Controls the amount of light that enters the pupil.

•Dim light: Pupil opened wide

•Bright light: Pupil partially closed

The Iris

Entrance of Light

Light enters the through the transparent cornea, where most of the bending of light takes place. The white dot in the lens is the reflection of light.

•Makes adjustments for focusing on objects at different distances.

•Muscles attached to the lens control its shape.

•Distant objects: the muscles relax leaving the lens thin.

•Nearby objects: muscles contract thickening the lens.

The Lens

Diagram of Eye

• The eyeball and the muscles that control its movement. The cornea and the lens focus the light rays onto the back of the eye. The lens controls the focusing the object for near and far objects by becoming more of less round.

Retina

• Light rays hit the retina on a spot called the fovea. The optic nerve is also connected to the retina, where it causes a blind spot within the eye.

•Rods: sensitive to light and dark

•Cones: responsible for seeing color, each cone is sensitive to a particular color.

•Colorblindness: when cones are not receptive to colors, most often red and green, rare, but more common in males than females.

Rods and Cones

•Difficulty seeing an object at a distance, but can see clearly if object is nearby.

•Occurs when the eyeball is too long and the image falls in front of the retina instead of directly on it.

•Lens of eye is too convex

Nearsighted

•Can see distant objects clearly, but close up objects are difficult to see.

•Occurs when the image is focused behind the retina.

•Lens of eye is not convex enough.

Farsighted

Bioluminescence

Polarized Lenses and Filters

• Polarized filter is made up of tiny slits, only the light waves that are vibrating in the same direction as the slits can pass through

Optical Instruments

• Cameras • Telescopes• Microscopes

Lasers• Lasers is a devise that produces an intense

beam of light• They are used in medicine, measurement, and

industries

Fiber Optics

• Fiber optics are strands of glass, some smaller than the human hair, that can transmit more information than ordinary wires.

• They transmit information as flashes of light at a higher frequency than radio waves

Do you feel like this?

What you need to know.