The Student Will Demonstrate an Understanding of the Properties and Behaviors of Waves

Standard 8.P.3:

The student will demonstrate an understanding of the properties and behaviors of waves.

Performance Indicator
8.P.3A.3 Analyze and interpret data to describe the behavior of waves (including refraction, reflection, transmission, and absorption) as they interact with various materials.

6 BEHAVIOR OF WAVES: REFLECTION,REFRACTION, DIFFRACTION, TRANSMISSION (TRANSPARENT, TRANSLUCENT, & OPAQUE), ABSORPTION, CONSTRUCTIVE INTERFERENCE

DESTRUCTIVE INTERFERENCE

Reflection is the bouncing back of a wave when it meets a surface or boundary that does not absorb the entire wave’s energy. All types of waves can be reflected.

• Reflections of sound waves, for example, are called echoes and help bats and dolphins learn about their environments.

• Planemirrors and other smooth surfaces reflect light to form clear images.
• Plane Mirror ,The color of an object & Echo, Echolocation, Waves Bouncing off cliffs, ball bouncing from the wall
• Echolocation is the use of sound waves and echoes to determine where objects are in space.BATS, HUMANS, DOLPHINS and other animals use Echolocation.

1. REGULAR REFLECTION: Occurs when parallel rays of light hit a smooth surface. The image will appear clear.

1. DIFFUSE REFLECTION: Occurs when parallel rays of light hit an uneven surface. The image will not be clear or you either can not see it.

MIRRORS

1. PLANE MIRROR: A FLAT SHEET OF GLASS THAT HAS A SMOOTH, SILVER-COLORED COATING ON ONE SIDE.

• PRODUCES A CLEAR, VIRTUAL, AND UPRIGHT IMAGE THAT IS THE SAME SIZE AS THE OBJECT.
• THE IMAGE YOU SEE IN A PLANE MIRROR IS AVIRTUAL IMAGE.
• VIRTUAL IMAGE: AN IMAGE THAT FORMS WHERE LIGHT SEES TO COME FROM. (VIRTUAL DESCRIBES SOMETHING THAT DOES NOT REALLY EXIST.)- THE OBJECT IS BETWEEN THE MIRROR AND FOCAL POINT. YOUR IMAGE APPEARS TO BE BEHIND THE MIRROR, BUT YOU CAN’T REACH BEHIND THE MIRROR AND TOUCH IT.

1. CONCAVE MIRROR: A MIRROR WITH A SURFACE THAT CURVES INWARD LIKE THE INSIDE OF A BOWLCAN REFLECT PARALLEL RAYS OF LIGHT SO THAT THEY MEET AT A POINT (FOCAL POINT).

• CAN PRODUCE REAL OR VIRTUAL IMAGES
• REAL IMAGES: FORMS WHEN LIGHT RAYS ACTUALLY MEET. THE OBJECT IS FATHER AWAY FROM THE MIRROR THAN THE FOCAL POINT.

1. CONVEX MIRROR: A MIRROR WITH A SURFACE THAT CURVES OUTWARDREFLECT PARALLEL RAYS OF LIGHT THAT SPREADS OUT BUT APPEARS TO COME FROM A FOCAL POINT BEHIND THE MIRROR.

• PRODUCES A VIRTUAL IMAGE THAT IS ALWAYS SMALLER THAN THE OBJECTALLOWS YOU TO SEE A LARGER AREA

Refractionis the bending of waves caused by a change in their speed as they pass from one medium to another. As waves pass at an angle from one medium to another, they may speed upor slow down. The greater the change in speed of the waves, the more the waves will bend.

• Refraction of light going from air through a convex lens, for example, can make images appear larger as the light waves bend.

• Prism, Magnifying Glass, Convex lenses, Glasses, Drop of water on letters, Rainbow, Anything that is being magnified
• Prisms or diffraction gratings separate white light into its different components or colors by bending the light at different angles depending on the frequencies of the light passing through the prism or diffraction grating. Different colors of light have different frequencies.

• The higher the index of refraction of a medium, the more it bends light.
• The index of refraction of water is 1.33. The index of refraction of glass is about 1.5. So light is bent more by glass than by water.

• SOUND TRAVELS FASTEST THROUGH A SOLIDTHE SPEED OF LIGHT TRAVELS THE FASTEST IN GAS.

• ANYTIME YOU LOOK THROUGH BINOCULARS, A CAMERA, OR EYEGLASSES, YOU ARE USING LENSES TO BEND LIGHT.
• THE TYPE OF IMAGE FORMED BY A LENS DEPENDS ON THE SHAPE OF THE LENS AND THE POSITION OF THE OBJECT.

1. CONCAVE LENS IS THINNER IN THE CENTER THAN AT THE EDGES. WHEN LIGHT RAYS TRAVELING PARALLEL TO THE OPTICAL AXIS PASS THROUGH A CONCAVE LENS, THEY BEND AWAY FROM THE OPTICAL AXIS AND NEVER MEET.

• CONCAVE LENS CAN PRODUCE ONLY VIRTUAL IMAGES BECAUSE PARALLEL LIGHT RAYS PASSING THROUGH THE LENS NEVER MEET.
• ALWAYS PRODUCES A VIRTUAL IMAGE THAT IS UPRIGHT AND SMALLER THAN THE OBJECT. MAKES THINGS APPEAR SMALLER.

1. CONVEX LENS IS THICKER IN THE CENTER THAN AT THE EDGES. AS LIGHT RAYS PARALLEL TO THE OPTICAL AXIS PASS THORUGH A CONVEX LENS, THEY ARE BENT TOWARD THE CENTER FO THE LENS.

• A CONVEX LENS ACTS LIKE A CONCAVE MIRROR, BECAUSE IT FOCUSES RAYS OF LIGHT.
• CAN FORM A REAL OR VIRTUAL IMAGE
• IF A CONVEX LENS IS HELD NEAR AN OBJECT, THE OBJECT LOOKS BIGGER BECAUSE THE LENS BENDS THE LIGHT RAYS INWARD. THE EYES TRACE THE LIGHT RAYS BACK IN STRAIGHT LINES AND SEE A VIRTUAL IMAGE THAT IS MAGNIFED.
• WHEN AN OBJECT IS BETWEEN THE LENS AND THE FOCAL POINT, THE REFRACTED RAYS FORM A VIRTUAL IMAGE.
• IF THE OBJECT IS OUTSIDE THE FOCAL POINT, THE REFRACTED RAYS FORM A REAL IMAGE ON THE OTHER SIDE OF THE LENS. THE REAL IMAGE CAN BE SMALLER, LARGER, OR THE SAME SIZE OF THE OBJECT.

WHAT ARE THEY USED FOR?

DIFFRACTION IS WHEN WAVES BEND AROUND BARRIERS OR PASS THROUGH AN OPENING IN A BARRIER, IT BENDS AND SPREADS OUT.

• Diffraction patterns are determined by both the size of the opening and the wavelength
• How does wavelength affect diffraction? The nearer the slit size is to the wavelength, the more the wave will diffract.

Transmission of waves occurs when waves pass through a given point or medium.

• Sound waves are transmitted through solids, liquids, and gases.
• Light travels in a straight line but when it hits an object it can be transmitted(pass through)
• KEY WORDS: WHEN A WAVE PASSES THROUGH

Light waves are transmittedthroughtransparent materials (may be clear or colored material such as filters) that allow most of the light that strikes them to pass through them. Only a small amount of light is reflected or absorbed. Opaquematerials allow no light waves to be transmitted through them.

Translucent materials transmit some light, but cause it to be scattered so no clear image is seen.

Absorption of certain frequencies of light occurs when the energy is not transferred through, or reflected by, the given medium.

• Objects or substances that absorb any wavelength of electromagnetic radiation become warmer and convert the absorbed energy to infrared radiation.
• Absorption is the disappearance of an EM wave into the medium
• Absorption can cast shadows
• Absorption happens when the medium has the ability to absorb the energy of the wave
• When the wave is absorbed, its energy is transferred to the medium and the wave is gone

Theater Curtains

The color Black

Standard 8.P.3 Students will demonstrate an understanding of the properties and behaviors of waves.

Performance Indicator 8.P.3A.4 Analyze and interpret data to describe the behavior of mechanical waves as they intersect.

• Waves interfere with each other.
• Interference is the interaction between waves that meet.
• The extremes of what can happen are called constructive interference and destructive interference

Interference may be constructive:

• A crest will interfere with another crest constructively to produce a larger crest and a trough will interfere to produce a larger trough.
• Compressions interfere constructively with each other as do rarefactions.
• Constructive Interference – 2 waves combine to form a new wave with a larger amplitude.

Interference may be destructive:

• A crest will interfere with a trough to lessen or cancel the displacement of each.
• Compressions interfere with rarefactions to lessen or cancel the displacement of each.
• Destructive Interference – 2 waves combine to produce a wave with a smaller amplitude.

SOUND WAVES

• Sound waves interfere with each other changing what you hear.
• Destructive interference makes sounds quieter; constructive interference makes sounds louder.
• Sound waves reflect in tubes or some musical instruments to produce standing waves which reinforce sound through constructive interference to make the sound louder.

PITCH & FREQUENCY

PITCH is the human perception of frequency.

How high or how low a sound seems to be depends on frequency.

High notes have high frequencies, and low notes have low frequencies.

THE DOPPLER EFFECT

The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding.