WAVES Unit 3 Sources: Ck12.org
BELLRINGER DAY 01 1. How do you think energy travels? 2. Are all waves the same? Explain.
LONGITUDINAL WAVES Amplitude, Rarefaction, and Compression
WHAT ARE WAVES? Waves are the way energy moves from place to place Waves are everywhere: Sound moves from a mouth to an ear by waves. Light moves from a light bulb to a book page to your eyes by waves.
Some waves we will be discussing include: Transverse Waves Longitudinal Waves Sound Waves Electromagnetic Waves TYPES OF WAVES
LONGITUDINAL WAVES Longitudinal (compressional) waves are waves where particles of the medium vibrate in a direction that is parallel to the direction that the wave travels. Examples include: Primary (P) waves from earthquakes; sound waves
CHARACTERISTICS OF LONGITUDINAL WAVES Compression: Places where the particles crowd together in the wave Rarefaction: Places where the particles spread farther apart in the wave Amplitude: The height of the wave
P (Primary) Waves during an earthquake EXAMPLES OF LONGITUDINAL WAVES The disturbance that causes an earthquake sends longitudinal waves through underground rocks in all directions away from the disturbance.
BELLRINGER DAY 02 Draw a longitudinal wave and label compression and refraction on your wave.
WAVE PROPERTIES Amplitude, Period, Frequency
TRANSVERSE WAVES A transverse wave is a wave where the particle moves perpendicular to the medium. Examples include: S (secondary) earthquake waves, electromagnetic waves
PERIOD AND FREQUENCY The time interval required for one complete wave to pass a point is called the period. During the period of the wave, an entire wavelength from one crest to the next crest passes a position. The number of waves that pass a single position in one second is called the frequency. These numbers are inverses-the longer the period, the lower the frequency, and vice versa Frequency is measured in Hertz (Hz)
AMPLITUDE The highest point from the center line of the wave is called the crest The lowest point from the center line of the wave is called the trough Amplitude is the height of the wave, or the maximum point of the crest and trough Wavelength is the distance between two like points on a wave
VELOCITY The velocity of a wave can be expressed as the waves distance over time.
BELLRINGER DAY 03 1. What are the two type of waves? 2. In which wave does the particles vibrate in the same direction as the wave? 3. In which wave does the particles vibrate perpendicularly to the direction of the wave? 4. Draw a transverse wave and label the amplitude, frequency, and wavelength.
WAVE EQUATIONS Solving for wavelength, frequency, and speed
WAVE EQUATIONS Because there is a relationship among wave velocity, frequency, and wavelength, we can use these numbers to solve wave problems
WAVE EQUATION EXAMPLE A wave has a frequency of 262 Hz has a wavelength of 1.29 m. What is the velocity of the wave? V w = λƒ V= (1.29) x (262) =338m/s
BELLRINGER DAY 4 Solve: A wave has frequency of 50 Hz and a wavelength of 10 m. What is the speed of the wave? Solve: A wave has frequency of 5 Hz and a speed of 25 m/s. What is the wavelength of the wave?
CLASSIFYING WAVES Mechanical, Electromagnetic, and Surface Waves
MECHANICAL WAVES A Mechanical Wave is a disturbance in matter that transfers energy through the matter Remember, matter is anything that has mass and takes up space A mechanical waves starts when matter is disturbed. A source of energy is needed to disturb matter and start the mechanical wave. Example: A drop of water in a lake causes waves to spread outwards. The drop of water is where the energy comes from.
MECHANICAL WAVES Energy of a mechanical wave can travel only through matter. The matter through which the energy travels is called the medium When the waves pass through the medium, the particles just vibrate in place. As they do, they disturb the particles next to them and pass the energy on, and on, and on The particles don t actually travel-only the energy travels through the medium Examples of mechanical waves include transverse, longitudinal, and surface waves
TYPES OF MECHANICAL WAVES
SURFACE WAVES Surface waves travels along the surface of a medium Example: An ocean wave travel on the surface of water between the ocean and air-caused by wind energy Surface waves are a combination of transverse waves that move up and down, and longitudinal waves that move parallel. Because they move up and down and back and forth, they have a circular motion.
ELECTROMAGNETIC WAVES Electromagnetic waves are waves that consist of vibrating electric and magnetic fields. Like other waves, they transfer energy from place to place Electromagnetic Radiation: The transfer of energy by electromagnetic waves They can transfer energy through matter, or through space It is a transverse wave, but not a mechanical transverse wave because it can travel through space Because they travel through space, no energy is lost as they travel (ex. Solar energy) When these wave reach the surface, they can be reflected back, refracted, or diffracted Travel very fast!!
BELLRINGER DAY 5 Choose and describe one of the waves we discussed yesterday. Your description should include: Type of wave How the wave travels Characteristics of the wave
QUIZ Properties of Waves and Wave Equations
BELLRINGER DAY 6 1. Why do surface waves have a circular motion? 2. What is the difference between and mechanical wave and an electromagnetic wave?
REFLECTION AND REFRACTION Examining Waves
REFLECTION Wave reflection is when the wave strikes a surface and bounces back Examples: Your image in a mirror, an echo The law of reflection says the angle of incidence is equal to the angle of reflection
WAVE REFLECTION Echolocation-the process of locating objects by emitting sounds & interpreting the sound waves reflected back. Many animals use echolocation-can you think of any?
WAVE REFLECTION SONAR (Sound Navigation and Ranging) Used to navigate and determine the distance or range to objects Uses the reflection of underwater sound waves to detect objects. Emits a sound pulse and measures the time for the pulse to travel to the object and return. RADAR (Radio Detection and Ranging) Used to find the speed of an object by sending out radio waves and measuring the time it takes them to return.
Ultrasound High frequency sound waves Uses: Breaking up and removing dirt buildup on jewelry Detect and monitor pregnancy, heart disease, cancer, etc. Produce images of some internal structures Sound bounces off structure and is converted to electrical signals which are then turned into pictures. WAVE REFLECTION
REFRACTION Wave refraction is the bending of a wave caused by a change in speed as it moves from one medium to another Greater the change in speed, the more the wave bends
REFRACTION IN WATER Light from Air to Water bends towards Normal Light from Water to Air bends away from Normal
DIFFRACTION Wave strikes an object and the wave changes direction. You can hear the lunch room long before you see it because the wavelength of sound are similar in size to the doorways. They diffract around the door and spread down the hallway.
BELLRINGER DAY 7 1. Provide an example of how wave reflection is used in real world application. 2. What is the difference between transverse and longitudinal waves?
BELLRINGER DAY 8 1. Label the parts of the transverse wave pictured below:
WAVE INTERFERENCE Constructive and Destructive
WAVE INTERFERENCE Wave interference is when two or more waves overlap and combine to form a new wave.
Said to be In Phase CONSTRUCTIVE INTERFERENCE
Said to be Out of Phase DESTRUCTIVE INTERFERENCE
STANDING WAVES Waves that are equal in wavelength and amplitude but traveling in opposite directions continuously interfere with each other Node- Place where the two waves always cancel each other. Always stays in the same place.
Gives violins their rich musical sound Flutes cause standing waves in the air Waves in drums happen in the skin that is stretched tight. STANDING WAVES
OTHER EXAMPLES OF INTERFERENCE Soup bubbles-light reflecting on the front and back side of the thin film of the bubble interfere, resulting in colors being enhanced
BELLRINGER DAY 9 1. What is the difference between constructive and destructive interference? 2. Give a real world example of wave interference.
REVIEW Waves
DAY 10 Test Day