Waves transmit energy but not matter.

Transcription

1 Wave Notes Waves transmit energy but not matter. Energy is the ability to cause something to happen or change. Waves are a repeating disturbance, vibration, or movement that transfers or moves energy from place to place. Waves can carry energy through empty space or a medium without transporting matter. Pull Pull Medium - material through which waves can travel. A medium can be a solid, liquid, or gas, or a combination of these. Pull 1

2 Types of Waves: Distinguish btw mechanical and electromagnetic waves. Mechanical waves are waves that travel through matter. The particles of matter vibrate by pushing together and moving apart, or by moving up and down as the waves travel through them to transfer the energy through the medium. They require particles to vibrate. Sound waves cannot be transferred or transmitted through space. Why? Ex. Sound waves, water waves, waves that travel down a rope. Electromagnetic waves involve electric and magnetic fields. They are waves that can travel through empty space where matter is NOT present. Electromagnetic waves transfer energy through space instead of transferring energy from particle to particle as is done by mechanical waves. Ex. radio waves, microwaves, infrared rays, visible light, ultraviolet rays, x-rays, and gamma rays. Pull 2

3 3

4 Properties of Waves Wavelength the distance between one point on a wave and the nearest point just like it. the greater the energy carried by the wave, the shorter the wavelength. Pull Frequency the number of full wavelengths that pass a point each second. The greater the energy carried by the wave, the greater the frequency. Pull Frequency and wavelength are inversely proportional. As frequency increases, wavelength decreases. Pull 4

5 5

6 7Iv4GmyXsCQ on a string/wave on a string_en.html XbjFn3aqE 6

7 Properties of Waves Amplitude the greatest that vibrations in a wave move from their normal position when a wave passes by. The greater the amplitude, the greater the energy. Pull Speed the distance per time that a given wave travels. A particular type of wave has a wave speed that is constant in a specific medium or in space. As a wave enters a different medium, the wave's speed changes. Waves travel at different speeds in different mediums. All electromagnetic waves travel at the same speed in empty space 300 million m/sec Pull 7

8 8

9 Wave Motion (transverse wave) Transverse Wave -The particles of matter move back and forth at right angles to the direction in which the wave travels. Movement of particles Direction of wave 9

10 Parts of a Transverse Wave Pull Pull 10

11 11

12 Label the parts of the transverse wave by sliding the name next to the part. wavelength Crest trough amplitude Click here for Review game correct answers 12

13 Wave Motion (compressional wave) Compressional Waves/ Longitudinal -cause particles in matter to move similar to a push and pull along the same direction in which the wave travels 13

14 Parts of a Compressional Wave Pull Pull 14

15 15

16 Label the parts of the compressional wave by sliding the name next to the part. rarefaction wavelength compression amplitude Do student demo now. 16

17 Types of mechanical and electromagnetic waves Pull Sound wave (compressional) Rope wave (transverse) Electromagnetic wave (transverse) Ready to sing?! 17

18 18

19 Wave Speed: Wave Speed = frequency X wavelength V = F λ v = Phase speed or speed of the wave measured in m/s, f = frequency of the wave measured in Hertz (Hz), λ = (Lambda)wavelength of the wave 19

20 Refraction - bending of waves caused by change in their speed as they pass from one medium to another. Reflection - the bouncing back of a wave when it meets a surface that does not absorb the entire wave's energy. Absorption - occurs when the energy is not transferred through the given medium or space. Transmission - occurs when waves pass through a given point or medium. Absorption Reflection Wave Behavior Match the term with the correct illustration Refraction Transmission Answers 20

21 Transmission depends on the material. Opaque - absorbs most of the light. Impenetrable by light.ex. book, blanket Translucent - transmits some light. Transmitting light but not enough to distinguish distinct images. Ex. sunglasses, wax paper Transparent - all light passes through. Transmits light so that objects can be seen as if there were no material blocking the object. Ex. glass, clear water 21

22 Transmission of Light Move the circle over one of the stars. Then, move the correct term next to the image shown. opaque transparent translucent answers 22

23 Homework Practice 1.Mac and Tosh are resting on top of the water near the end of the pool when Mac creates a surface wave. The wave travels the length of the pool and back in 25 seconds. The pool is 25 meters long. Determine the speed of the wave. 2. Two boats are anchored 4 meters apart. They bob up and down, returning to the same up position every 3 seconds. When one is up the other is down. There are never any wave crests between the boats. Calculate the speed of the waves. 3. Sound waves are longitudinal, but light waves are transverse. T/F 4. Light waves can travel through a vacuum, but sound waves require a medium. T/F 5. Transverse waves travel faster than longitudinal waves. T/F 23

24 Frequency (HZ) Wavelength (m) Velocity (m/sec)

25 Sound Waves and the Parts of the Ear Sound travels as a compressional wave. Sounds with greater amplitude will be louder; light with greater amplitude will be brighter. Sound waves are gathered by the outer ear which is shaped to help capture the sound waves energy transferred in particles of air and send them through the ear canal, which transfers them to the eardrum. The vibrations of air particles cause the eardrum to vibrate. If the vibrations follow each other slowly low frequency the sound is heard as a low pitch. If the vibrations follow each other in rapid succession high frequency, the sound is heard as a high pitch. 25

26 Sound Waves and the Parts of the Ear Sound waves with large amplitudes push on the eardrum with more force and are heard as loud sounds. Sound waves with small amplitudes push on the eardrum with less force and are heard as soft sounds. Vibrations from the ear drum are transmitted to three small bones of the middle ear, which transmit the vibrations to the inner ear. The vibrations in the liquid of the inner ear cause the tiny hairs to vibrate. The vibrating tiny hairs transmit the energy to nerves attached to the hairs. The nerve impulses are transmitted to the brain and interpreted as hearing. 26

27 Sound Waves Some sounds are loud. Some sounds are soft. This is called Volume Intensity Sound with a greater amplitude has a greater intensity. 27

28 Some sounds are high.some sounds are low. This is called Pitch Pitch The human perception of the frequency of sound. Sounds with low frequency have a low pitch. Sounds with a high frequency have a high pitch. 28

29 Echoes sounds that reflect off of surfaces. Reverberation repeated echoes. Echolocation process by locating objects by sounds bouncing off of them. 29

30 30

31 31

32 32

33 Waves of the Electromagnetic Spectrum These are waves that are caused by the interaction of electric and magnetic fields. These waves can travel through empty space. The speed of light in a vacuum is 300 million meters per second. In one year, light can travel 9.5 trillion kilometers. This is known as a LIGHT YEAR. The waves are classified according to the wavelength. The following are the types of waves in the spectrum from longest wavelength to the shortest. Remember that if the wavelength is long, the frequency is low! Radio Waves link to Electromagnetic spectrum Microwaves Infrared Waves Visible Light Ultraviolet Rays link to Wavelength Order Practice X- Rays Gamma Rays 33

34 Visible Light Visible light only makes up a small portion of the electromagnetic Spectrum. White light is a blend of different colors. A white surface reflects all wavelengths to our eyes. An object that is black, absorbs all wavelengths. An object that is green absorbs all wavelengths except green. Red light = longest wavelength. violet light= shortest wavelength. A prism is a device that can refract (bend) light each color having its own wavelength. Yellowish green is detected best by human eye (can only see light between nanometers). Diffraction grating is a material with evenly spaced slits that separate white light into colors. Rainbows are refracted white light created by tiny droplets of water suspended in the atmosphere. ROYGBIV 34

35 Parts of ear Echolocation Reverberation 35

36 pinna semi - circular canals anvil stirrup auditory nerve eardrum ear canal cochlea hammer 36

37 37

38 Mr Parr Light up close How eye functions seeing the light the eye vision and perception (30) Slim Goodbody How we see Mr Parr light and color _Y&feature=player_detailpage Near and far sightedness LENS 38

39 Parts of the Eye Match the part of the eye with the correct function by moving the correct term next to the function. retina iris pupil Transparent protective covering Ring of muscle that contracts and expands due to changes in light cornea optic nerve lens Bonus Allows light to enter the eye Convex in shape. It refracts light and forms an image on the lining of the eyeball. Controlled by ciliary muscles to help maintain focus Inner lining of the eyeball that is made up of millions of cells called rods and cones. Receives signals from the rods and cones and transmits the image to the brain for interpretation 39

40 40

41 Identify the parts of the eye. Move the word next to the correct position. cornea optic nerve iris lens pupil retina Correct answers 41

42 How We See an Image 42

43 Convex Lens a lens that is thicker in the center than at the edges. Light rays are bent inward when traveling through this type of lens. The image is similar to an image formed by a concave mirror. The image seen through the lens is inverted and smaller than the object. Concave Lens a lens that is thicker at the edges than in the middle. The light rays are bent outward when traveling through this type of lens. The image is similar to that of a convex mirror. The image is upright and smaller than the object. 43

44 Types of Lenses convex concave

45 Farsightedness cannot see objects that are close clearly. The retina is too close to the eye lens. convex focal point light Which type of lens will correct this person's eyesight? concave

46 Nearsightedness cannot see objects that are far away clearly. The retina is too far from the eye lens. focal point light Which type of lens will correct this person's eyesight? convex concave

47 What are Bonus (slide the word to reveal the answer) cells in the retina that distinguish among black, white and gray and cells in the retina that react to color? back 47

48 Label the parts of the wave by sliding the name next to the part. wavelength Crest amplitude trough back 48

49 back 49

50 Identify the parts of the eye. Move the word next to the correct position. Answers pupil cornea retina optic nerve lens iris 50

51 Parts of a Wave Wavelength - the distance between one point on a wave and the nearest point just like it. The greater the energy carried by the wave, the smaller the wavelength. Crest - the top of a wave. trough - the bottom of a wave. Frequency - the number of full wavelengths that pass a point each second. The greater the energy carried by the wave, the greater the frequency. * Frequency and wavelength are inversely proportional- As frequency increases, wavelength decreases Amplitude - the greatest distance that vibrations in a wave move from their normal position when a wave passes by. The greater the amplitude, the greater the energy. Speed - the distance per time that a given wave travels. Waves travel at different speeds in different mediums. All electromagnetic waves travel at the same speed in empty space million m/sec. 51

52 Transmission of Light Answers Transmission depends on the material. Opaque - absorbs most of the light. Ex. book, blanket Translucent - transmits some light. Ex. sunglasses, wax paper Transparent - nearly all light passes through. Ex. glass, clear water Move the circle over one of the stars. Then, move the correct term next to the image shown. opaque translucent transparent Back 52

53 Wave Behavior Refraction - bending of waves caused by change in their speed as they pass from one medium to another. Reflection - the bouncing back of a wave when it meets a surface that does not absorb the entire wave's energy. Absorption - occurs when the energy is not transfered through the given medium or space. Transmission - occurs when waves pass through a given point or medium. Match the term with the correct illustration Absorption Refraction Transmission Reflection Back 53

54 Place the wavelengths in order from the shortest to the longest Answers Microwaves Infrared Visible Rays Gamma Rays Ultraviolet X Rays Radio Waves Back 54

55 Place the wavelengths in order from the shortest to the longest Answers Gamma Rays Ultraviolet Infrared Radio Waves X Rays Visible Rays Microwaves 55

56 Intensity The amount of energy that a wave carries past a certain area each second. Sound with a greater amplitude has a greater intensity. Pitch The human perception of the frequency of sound. Sounds with low frequency have a low pitch. Sounds with a high frequency have a high pitch. Echoes sounds that reflect off of surfaces. Reverberation repeated echoes. Echolocation process by locating objects by sounds bouncing off of them. 56

57 57

58 58

59 Attachments j wav http.doc Waves.pptx