1. Waves carry energy from one place to another
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WAVES
Waves carry energy from one place to another

2. NATURE OF WAVES
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Waves (Def.) – A wave is a disturbance that transfers ENERGY, but not matter.

3. NATURE OF WAVES Two types of waves:
1.MECHANICAL WAVES- waves that use a medium(matter) to transfer energy
There are two kinds of mechanical waves:

4. Transverse Waves
Energy causes the matter in the medium to move up and down at right angles (perpendicular) to the direction of the wave
Examples: shaking a rope, water waves

5. Transverse Waves
crest
trough

6. Compressional Waves
Energy causes the matter in the medium to move back and forth (parallel) along the same direction that the wave travels
Examples: a slinky toy, sound waves

7. Compressional Waves
compressional
transverse

8. Compressional Waves Sound Waves are Compressional Waves
Sound travel faster through solids than gases
compressions
rarefactions

9. NATURE OF WAVES Two types of Waves
2. ELECTROMAGNETIC WAVES - waves that can travel through space where there is no matter, therefore no medium is needed

10. Electromagnetic Waves
Speed of light
300,000 km/sec
186,000 mi/sec
Travel faster in gases than solids
There are seven kinds of E-M waves:

11. Electromagnetic Spectrum
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12. Electromagnetic Spectrum
Invisible Spectrum
Radio Waves
Def. – Longest wavelength & lowest frequency.
Uses – Radio & T.V. broadcasting.
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13. Electromagnetic Spectrum
Radio Waves
AM – amplitude modulation
Carries audio for T.V. Broadcasts
Longer wavelength so can bend around hills
FM – frequency modulation
Carries video for T.V. Broadcasts

14. Electromagnetic Spectrum
Invisible Spectrum (Cont.)
Microwaves
Are more like high frequency radio waves
Causes molecules to vibrate making them hot
Can cause cataracts

15. Electromagnetic Spectrum
Invisible Spectrum (Cont.)
Infrared Rays
Def – Light rays with longer wavelength than visible red light.
Uses: Cooking, Medicine, T.V. remote controls
WE give off infrared waves!

16. Electromagnetic Spectrum
Invisible spectrum (cont.)
Ultraviolet rays.
Def. – EM waves with frequencies slightly higher than visible light
Uses: food processing & hospitals to kill germs’ cells
Helps your body use vitamin D.

17. Electromagnetic Spectrum
Invisible Spectrum (Cont.)
X-Rays
Def. - EM waves that are shorter than UV rays.
Uses: Medicine – Bones absorb x-rays; soft tissue does not.
Lead absorbs X-rays.

18. Electromagnetic Spectrum
Invisible spectrum (cont.)
Gamma rays
Def. Highest frequency EM waves; Shortest wavelength. They come from outer space and other radioactive substances.
Uses: cancer treatment.

19. Parts of a Wave Wavelength
Distance from crest to crest OR trough to trough
wavelength

20. Parts of a Wave Wavelength For a compressional wave:
distance between the center of one compression to the center of the next compression, same with rarefactions

21. Parts of a Wave Amplitude (related to the wave’s energy)
one-half the distance between crest and trough
Rest position

22. Parts of a Wave Frequency
The number of wavelengths that pass a given point in 1 sec.
This wave’s
Frequency is 4 Hz.
What is this wave’s
Frequency?

23. Parts of a Wave What is the relationship b/w frequency and wavelength?
As wavelength _______, frequency ________.
Therefore, long ________, means low ________.

24. Parts of a Wave
Speed
Equals the wavelength times frequency
v = f

25. Electromagnetic Spectrum
Visible Spectrum – Light we see
C O L O R
Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet.
Longest to Shortest Wavelength.

26. Color of Light (Cont.) Color of Objects
White light is the presence of ALL the colors of the visible spectrum. White light is due to the reflection of light.
Black is the result of the absorption of ALL the colors and no light is reflected back.
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27. Color of Light (Cont.) Primary Colors of Light
Three colors that can be mixed to
produce any other colored light
Red + blue + green
Complimentary Colors of Light
Two complimentary colors combine
to make white light-Magenta,Cyan,Yellow

28. Color of Light Transparent Objects: Translucent: Opaque:
Light transmitted because of no scattering
Color transmitted is color you see.
The object is see-through basically
Translucent:
Light is scattered and transmitted some.
Opaque:
Light is either reflected or absorbed.
Color of opaque objects is color it reflects.

29. How You See Retina – Rods – Cones –
Lens refracts light to converge on the retina. Nerves transmit the image
Rods –
Nerve cells in the retina that are very sensitive to light and dark
Cones –
Nerve cells in the retina that help to distinguish color color

30. The eye

31. LIGHT & ITS USES Sources of Light
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Sources of Light
Incandescent light – light produced by heating an object until it glows.
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32. LIGHT & ITS USES Fluorescent Light –
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Fluorescent Light –
Light produced by electron bombardment of gas molecules
Phosphors absorb photons that are created when mercury gas gets zapped with electrons. The phosphors glow & produce light.

33. LIGHT & ITS USES
Neon light – neon inside glass tubes makes red light. Other gases make other colors.
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34. Behaviors of Light
Refraction – Bending of light due to a change in speed.

35. Behaviors of Light

36. Behaviors of light
Reflection – Bouncing back of light waves.

37. Behaviors of Light

38. Behaviors of Light Reflection Vocabulary
Optical Axis – Base line through the center of a mirror or lens
Focal Point – Point where reflected or refracted rays meet & image is formed
Focal Length – Distance between center of mirror/lens and focal point

39. Mirrors Plane Mirrors – Perfectly flat
Virtual – Image is “Not Real” because it cannot be projected
Erect – Image is right side up
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40. Reflection & Mirrors (Cont.) Convex Mirror Curves outward
Enlarges images.
Use: Rear view mirrors, store security…
CAUTION! Objects are closer than they appear!
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41. Mirrors Reflection & Mirrors (Cont.) Concave mirror Curves inward
Minimizes images
Use: make up mirrors, telescopes, dentist mirror, headlights

42. Lenses Convex Lenses Thicker in the center than edges.
Lens that converges (brings together) light rays.
Forms real images and virtual images depending on position of the object

43. Lens that is thicker at the edges and thinner in the center.
Lenses
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Concave Lenses –
Lens that is thicker at the edges and thinner in the center.
Diverges light rays
All images are erect and reduced.

44. Lenses
Vision – Eye is a convex lens.
Nearsightedness – Concave lenses expand focal lengths
Farsightedness – Convex lenses shortens the focal length.

45. How You See
Near Sighted – Eyeball is too long and image focuses in front of the retina
Far Sighted – Eyeball is too short so image is focused behind the retina.
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46. Behaviors of Light
Diffraction – Bending of waves around the edge of a barrier or through an opening. New waves are formed from the original. breaks images into bands of light & dark and colors.
Causes the edges of shadows to be blurry

47. Behaviors of light
Absorption- the transfer energy carried by light waves to particles of matter
When you shine a flashlight, the air particles absorb some of the energy from the light

48. The End…
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