1. Light

2. Electromagnetic Radiation  Electromagnetic waves (E.M.) are transverse waves produced by the motion of electrically charged particles (photons).  E.M. waves do not require a medium, and are therefore able to travel at 186,000 mi/s (300,000 km/s), the speed of light (which is an E.M. wave).

3. Electromagnetic Spectrum  The different electromagnetic waves are arranged in the electromagnetic spectrum in order of increasing frequency and decreasing wavelength.  The higher the frequency, the more photons (energy) per wave, and the more potentially harmful the wave is.

4. Low energy High energy

5. Radio Waves  Radio waves are the lowest frequency E.M. wave.  They are used primarily for communications, such as cell phones, t.v. and radio transmissions, and cordless devices such as phones, speakers, etc.

6. Microwaves  Microwaves are a type of radio wave. They are used in cell phones and microwave ovens.  At normal levels, microwaves are harmless.

7. Infrared Radiation  Infrared radiation transfers energy in the form of heat.  Examples include heat lamps and the warmth from the sun. Special types of film and cameras can show infrared radiation. This is called thermography.

8. Ultraviolet Light (U.V.)  U.V. rays are potentially dangerous at high levels or with prolonged exposure.  U.V. rays can cause sunburns and skin cancer, and kill bacteria and healthy cells.

9.  The ozone layer of the atmosphere blocks most u.v. rays from reaching the earth.  Using sunscreens with high S.P.F. ratings can also help protect your skin from u.v. rays.

10. X-Rays  X-rays are high frequency e.m. waves which are potentially dangerous at moderate levels.  X-rays can penetrate many materials such as skin, muscle, and many fabrics.

12. Visible Light  Visible light can be separated into 7 different colors. From lowest frequency to highest, they follow the acronym ROY G. BIV  When all 7 colors are combined together they produce white light.

13. Prisms & Rainbows  Prisms  Prisms: Separates white light into its component colors. The longer the wavelength, the less it will be bent by the prism.  Rainbows  Rainbows- light shining thru tiny droplets of water, each droplet acts as a prism

14. Color   The color of the object you see is the light that is reflected from its surface. All other colors are absorbed by the object.

15. Primary & Secondary Light Colors  primary colors  The 3 colors of light that can combine to form all other colors are primary colors –   a. Red, Blue, Green   i. Equal Red + Equal Blue = Magenta (secondary color)   ii. Equal Red + Equal Green = Yellow (secondary color)   iii. Equal Green + Equal Blue = Cyan (secondary color)   iv. Equal Red + Equal Green + Equal Blue = White Magenta Yellow Cyan

16. Pigments  Pigment  Pigment – substance that color other materials like paints, inks, etc   a. Primary Pigments are Cyan, Yellow & Magenta   b. Cyan + Yellow + Magenta = Black   c. Cyan + Yellow = Red   d. Yellow + Magenta = Red   e. Cyan + Magenta = Blue   f. The primary pigments are the secondary light colors! Blue Red Green

17. Compare Lights & Pigments   Three primary colors = three secondary pigments   Three primary pigments = Three secondary colors

18.  Transparent materials allow almost all visible light to pass through. Ex.: glass, plastic wrap Ex.: glass, plastic wrap

19.  Translucent materials allow a partial amount of visible light to pass through. Ex.: wax paper, shower doors, plastic milk jugs Ex.: wax paper, shower doors, plastic milk jugs

20.  Opaque materials stop almost all visible light from passing through. Ex.: drywall, thick curtains Ex.: drywall, thick curtains

21. Reflection & Mirrors   When light strikes an object   It is either reflected, absorbed or transmitted. Opaque: a material that reflects or absorbs the light – can’t see through it. -wood Transparent: The material transmits light – allows light to pass through it– glass Translucent: allows some light to pass through – can’t see image clearly – wax paper, frosted glass.

22. Kinds of Reflections   You see objects because light is reflected, bounced off of it.   Law of Reflection: Angle of incidence equals the angle of reflection– Angle coming in = angle going off   Regular Reflection: reflection off smooth surface – a mirror   Diffuse Reflection: Irregular or bumpy, uneven surface – wall

23. Refraction  RefractionBend  Refraction of Light: Bend or change direction   1. As light rays enter a new medium the cause light to bend   2. The denser the medium – the slower the light travels  Index of Refraction  3. Index of Refraction: a measure of how much a medium bends the light that travels through it.   4. The faster the beam, it will bend away from normal, the slower the beam, it will bend toward the normal.

24. 3 Types of Mirrors   Plane Mirror: a flat mirror – produces an image that is right side (virtual) up and the same size as the original object –   Concave Mirror: a mirror with a surface curved inward like a “cave” or a bowl. Light reflected comes together to meet at a Focal Point. Can produce virtual or real images   Convex Mirrors: A mirror w/ a curved surface facing outward Reflected rays appear to come from a focal point behind the mirror Images formed are always Virtual Concave mirrorConvex mirror Plane mirror

25. Real or Virtual?   Image: a copy of an object formed by reflected or refracted light   Virtual image: right side up appears to be coming from behind the mirror.   Real Image: is formed when reflected light rays actually meet at a point. The image is upside down (inverted),

26. Lens – Concave & Convex   Lenses – a curved piece of material used to bend light Convex lenses Convex lenses: cause light passing through to bend toward the focal point. (converging) The images produced depends on the position of the object Concave lenses Concave lenses: as light passes through, they are bent away from the center (diverging) Images produced are only virtual, not real Concave Lens Convex Lens

27. Polarized Light  Normal light will produce waves which vibrate in many different planes.  Polarized light is light which vibrates in only 1 plane. This is created by passing normal light through a polarized lens.

28.  Polarized lenses block all light waves except those moving in 1 particular plane.

30.  Polarized glass and lenses are effective at blocking out glare from the sun. As a result they are used in car windshields, sunglasses, and camera lenses. As a result they are used in car windshields, sunglasses, and camera lenses.

31.  A mirage is a visual distortion produced by the refraction of light.  Some mirages produce a mirror or a watery image, and others may make an object appear larger or smaller, nearer or further away.

33.  This device produces a false image, but not a true mirage.

40.  I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid. Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh?

41. Vision - Structure Need to know these structures & their function:  Ciliary muscle: ligaments attach the lens to these, they contract & stretch the lens allowing near & far focus  Vitreous humor: fluid inside eyeball maintains size & shape of the eye  Retina: contains the rods & cones that are sensitive to light  Choroid coat: middle layer of the eyeball  Sclera: the outer “whites of the eye”  Optic nerve: takes rod & cone impulse back to the occipital lobe for processing

42. Image Processing  Fovea –  Fovea – The central region where images focused is the fovea.  Rods – about 1 billion, sensitive to brightness, light and dark & movement  Cones – detect color, about 3 million. 3 types of cones, sensitive to red, blue & green wavelengths of light.  All rods & cones have nerve fiber attached, these collect at the back of the eye and form the optic nerve which carries the signal back to the eye.

43. Lasers & Coherent Light  Coherent light is visible light traveling at only 1 specific wavelength (resulting in 1 color). This wave has all of it’s crests and troughs aligned and travels in only 1 direction. A laser is an example of coherent light.

44.  A laser is a device used to create a beam of coherent light.

45. Lasers  In a laser, an electric current excites a material (like neon) and causes it to emit photons. These photons are enclosed inside the laser device where they bounce back and forth between 2 mirrors and becomes perfectly aligned (coherent light).

46.  Some of these photons, if they are aligned correctly, escape through a small portion of one of the mirrors. This is the laser beam.