Waves/Sound/Light (PS. 8 & 9)

I. Waves

A. Definitionà a disturbance that transfers energy through matter or space

II. Types of Waves

A. Transverse waves

1. Can travel with or without matter (medium)

2. Moves at rt. angles to the direction it travels (moves up and down as it goes)

3. Exampleà light (electromagnetic waves)

4. Parts of a traverse wave

A. ________________ D. __________________

B. ________________ E. _________________

C. _________________ F. _________________

B. Compression (Longitudinal) Wave

1. Must travel with matter (medium)

2. Moves in the same direction as it travels

3. Exampleà sound (caused by vibrations)

4. Parts of a compression wave

X. ___________________

Y. ___________________ Z. ___________________

C. Similar Parts among Wave Types

1. compression à ___________________

2. rarefactionà ____________________

III. Wave Properties

A. amplitude- measure of the amount of energy in a wave

1. Sound 2. Light a. determines intensity/loudness a. the greater the amplitude the b. units à decibel (dB) brighter the light c. possible hearing damage occurs at 120 dB

B. frequency- measures how often waves pass a certain point

1. measured in units called hertz (Hz)

2. Sound a. ________________- the highness/lowness of a sound

b. Human hearing range à 20 Hz – 20,000 Hz

3. Light a. As you move across the light spectrum, wavelength ________________and

frequency __________________

C. What is the relationship between wavelength and frequency?

1. If wavelength increases then frequency decreases 2. If wavelength decreases then frequency increases

IV. Wave Interactions/Movements

A. Reflectionà when a wave bounces off a surface

1. Angle of incidence =angle of reflection

2. Examples a. Sound- _____________________ b. Light- _____________________________

B. Refractionà bending of a wave as it changes speed

1. Example-a pencil in glass of water looks broken (light bends when it hits water) 2. Example- prism bends white light into the spectrum of colors (rainbow)

C. Diffractionà bending of a wave around an object

1. Example – water waves bend around people 2. Example – hear sounds from another room

D. Interferenceà interaction between 2 waves at the same place and time (waves combine)

1. Constructive à makes a bigger wave; increases intensity; results in louder sound/brighter light 2. Destructive à makes a smaller wave; decreases intensity; results in softer sound/softer light

F. Resonance à object vibrate at its natural frequency; applies to sound ex. Tuning fork, guitar strings, bridge swinging due to high winds

V. Properties of Sound

A. Sound Barrier

1. Definition à point when an object moves _____________________ than

the _______________________________________

2. ____________________– the sound made when something breaks the sound barrier

3. October 14, 1947 – Chuck Yeager breaks the sound barrier

B. Doppler Effect

1. Refers to ___________________________________ as an object approaches

2. Examples include ambulance/police sirens, car horns

C. Uses of Sound

1. Major (common) uses include _________________________________________________

2. Other uses of sound include:

a. Infrasound (subsonic) à refers to sounds ______________________;

*used to detect earthquakes, find oil

b. Ultrasound à refers to sounds ____________; * used in sonograms, removal of kidney stones, and dog whistles

3. __________________________ àuse of reflection to locate objects; ex. bats, dolphins

4. ____________________àSound Navigation and Ranging; used to locate objects under water

5. _____________________ à the study of sound

D. Speed of sound à about 345 m/s in air; the speed is affected by:

1. _________________________ - faster in warmer temps

2. _________________________ - faster in solids than liquids and gases

VI. Properties of Light A. What is Light?

1. Definitionà Light is an electromagnetic transverse wave caused by vibrating electric charges.

2. Speed of light – 300,000 km/s (186,000 miles/s); light year- distance light travels in one year.

3. Light Controversy – Particle or Wave?

a. Difference between waves and particles is not clear.

b. Light can behave like a packet of energy called a _________________________.

c. _______________________________ proved it is both a wave and a particle.

B. The Electromagnetic Spectrum – represents the entire range of visible and invisible light waves.

*** Refer to foldable for uses.

C. The Behavior of Light 1. Objects must reflect light to be seen; the reflection of light determines the color you see.

2. _______________________ materials do not allow light to pass through; no images

3. ____________________________– some light passes through it; fuzzy image

4. ________________________________ – all light passes through it; clear image

5. Objects that reflect light are illuminated (ex. Moon); objects that make their own light are luminous (ex. Sun)

6. Light and Color

a. __________________à determined by wavelength of light an object ____________

b. Objects appear to be_____________________ because they reflect all colors of light.

c. Objects appear to be _______________________because absorb all colors of light.

d. ______________________à transparent material that absorbs all colors except the color (s) it transmits.

D. Light Optics 1. Common Uses of Light- light bulbs, lasers, fiber optics, optical scanners.

2. ______________ à transparent device usually made of glass or plastic that refracts light.

a. __________________ à (draw a pic)

b. ___________________ à (draw a pic)

3. _____________________ à device with curved surfaces designed to reflect light. *Convex mirrors diverge light and produce a smaller, upright image. Concave mirrors converge light and produce an upright, magnified image if close and an inverted, smaller image if far away.

4. _________________________à uses mirrors and lenses to see far away objects

5. _____________________________à uses 2 convex lenses to magnify objects