2 What is light? Light is a form of energy Nothing travels faster than light (186,000 mi/sec)Our eyes can change visible light energy waves into something we can see
3 ELECTROMAGNETIC WAVES What is light?Visible light energy is just one form of light energy and it can be seen.Invisible light energy is light we cannot see:InfraredUltravioletRadioX-rayLight is a form of energy formed by a combination of electrical and magnetic rays=ELECTROMAGNETIC WAVES
4 Light Energy Like sound: Light travels in waves that have certain wavelengths and frequenciesIts speed is different in different materialsIt can be reflected or absorbed, or it can pass through an object
5 Light Energy Unlike Sound: Light is not a vibration Light can travel through a vacuumLight travels more slowly through water and airLight is a form of electromagnetic radiation
6 How light behaves.Light travels in a straight line in all directions from its source.It will continue to travel in a straight line until it hits something.When light hit something, different things can happen. It will be either:reflected,refracted, oropaque
8 Reflection Reflection-when light hits a particular surface and bounces back.
9 RefractionRefraction of Light: The bending of light due to a change in its speed. The differences are caused by the changing speed of the light as it transitions to different mediums. Example: A straw appears bent in a glass of water. A swimming pool appears shallower than it really is.
13 Transparent-Light and matter The waves can pass through the objectWhen light hits something it may be transparent.Transparent-allows almost all the light to pass through with very little bending or scattering of the rays. You can see through it.Examples: eyeglasses, empty clear glass, clear window.
14 The waves can be absorbed by the object Translucent- Light and MatterTranslucent- allows only some light to pass through, yet scatters and bends the rays. You can see through it, but not clearly.Examples:frosted glass, clouds, thin paper.The waves can be absorbed by the object
15 Opaque The waves can be scattered off the object. Opaque-light can not pass through, thus creating a shadow. Examples: cardboard, brick, solid wood, door.The waves can be scattered off the object.
16 How do we see color?Light contains all the colors of the rainbow: ROYGBIVColor is a product of visible light energy.Color is created when light waves vibrate at different frequencies.Most colors are made from mixing together three colors: red, blue, and green
17 Electromagnetic Spectrum Wavelength getting smaller = waves closer togetherThese waves are always transverse waves and do not need a medium to travel.
24 PupilThe round black parts of your eye that lets light travel through it .It controls the amount of light that enters the eyeIn the dark- pupils are bigger to let in more lightIn the light- pupils are smaller to let in less light.
25 CorneaCornea is the transparent outer layer of the eyeball. It covers the iris and the pupil.
26 Iris Iris is the colored part of the eye It is usually blue, green, or brownMuscles in the iris controls the pupil
27 LensLens are under the cornea and together they bend the light to project an upside image on the retina
28 Retina is the lining at the back of the eyeball that’s sensitive to light. It sends messages to the optic nerve. It is a like a movie screen. The retina is the back part of the eye that contains the cells that respond to light.These specialized cells are called photoreceptors.There are 2 types of photoreceptors in the retina: rods and conesRetina
29 Cones and RodsThe rods are most sensitive to light and dark changes, shape and movement and contain only one type of light-sensitive pigment. Rods are not good for color vision. The cones are not as sensitive to light as the rods. However, cones are most sensitive to one of three different colors (green, red or blue).
30 Optic NerveOptic Nerve is a bundle of nerves that sends messages between the retina and the brain.