Characteristics of Waves 8.P.3A.1 Construct explanations of the relationship between matter and energy based on the characteristics of mechanical and light waves

Waves Repeating disturbance or vibration that transfers or moves energy from place to place Created when a source of energy (force) causes vibrations Vibration is a repeated back-and-forth or up-and-down motion Waves carry energy through empty space or through a medium without transporting matter All waves can transmit energy through a medium Electromagnetic waves can transmit energy through empty space Medium is a material though which waves can travel. Solid, liquid, gas, plasma

Mechanical Waves Mechanical waves require the particles of the medium to vibrate in order for energy to be transferred Water Waves, Earthquake/seismic waves, sound waves, and waves that travel down a rope or spring Mechanical waves cannot be transferred or transmitted through empty space

Light Waves Electromagnetic waves Travel through matter or empty space Part of electromagnetic spectrum that is visible to the human eye

Movement of Waves Mechanical waves Matter particles vibrate by pushing together and moving apart parallel to the direction in which the wave travels are called “compressional” or “longitudinal waves” Place where wave is pushed together is called the “compression” Place that is moving apart is the rarefaction Sound/Seismic

Movement of Waves: Transverse Particles of matter in the medium vibrate by moving back and forth and perpendicular (Right Angles) to the direction the wave travels are transverse waves Highest point is the “crest” Lowest point is the “trough” Rope, water, slinky, string instrument Light waves are transverse that can travel without a medium

Properties of Waves 8.P.3A.2 Develop and Use Models to exemplify the basic properties of waves (including frequency, amplitude, wavelength and speed).

Frequency Measure of how many waves pass a certain point in a certain time. The higher the Frequency, the faster/the closer the waves are together. The higher the Frequency, the more energy carried by the waves Measured by hertz (Hz)

Wavelength Measure of the Distance from Crest A to Crest B Or Troughs Shorter Wavelengths are influence by Frequency Higher Frequency causes shorter the wavelength and greater the energy

Amplitude Measure of the distance of a line down the center of the wave to the crest or trough Middle Line is running on the plane the wave is moving on “Height” of the wave Greater the Force means Greater the amplitude and Energy carried In a Transverse Wave, Higher the Height, the Greater the Amplitude (Sound Waves) Greater Amplitude=Greater the Sounder (Light Waves) Greater Amplitude= Brighter the Light

Speed Distance a single wave travels in a certain time Speed determined by type of wave (Electromagnetic or Mechanical) and by the nature of the medium As a wave enters a different medium, the wave speed changes Each medium causes a different speed ALL FREQUENCIES of electromagnetic waves travel at the same speed in empty space How to calculate: Speed/Velocity equals the Frequency times the Wavelength V=f•λ

Behavior of Waves 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

Refraction Bending of waves caused by a change in their speed as they pass from one medium to another Waves may speed up or slow down as they pass at an angle from one medium to another Greater the change in speed of the waves, the more the waves will bend Refraction of light going from air through a convex lens, can make images appear larger as light waves bend Prisms or diffraction gratings separate white light into its different components or colors by bending light at different angles depending on the frequencies Different colors of light have different frequencies

Reflection 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 are called echoes Bats, dolphins, whales Plane mirrors and other smooth surfaces reflect light to form clear images

Transmission Occurs when waves pass through a given point or medium Mechanical waves (like sound) are transmitted through solids, liquids, and gases Light waves are transmitted through transparent materials which allow most of the light that strikes them to pass through Opaque materials 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 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

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

Interference Constructive Interfere with another wave (crest to crest) to produce a larger crest Interfere with another wave (trough to trough) to produce a larger trough 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 Sound waves interfere with each other changing what people hear Destructive- interference makes sound quieter Constructive- interference makes sound 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

Color 8.P.3A.5 Construct explanations for how humans see color as a result of the transmission, absorption, and reflection of light waves by various materials

Human Eye and color Light waves that have been emitted or reflected by an object, enter the cornea where the light is refracted through the pupil Light rays are refracted again to pass through the lens Convex shape Lens focuses light on the retina (back of the eye) Retina is composed of nerves that transfer the energy of light waves to the nerve impulses transmitted through the optic nerve to the brain for interpretation

Absorption and Reflection of Light Most materials absorb light of frequencies and reflect the light of other frequencies Material absorbs a certain frequency, the color of the frequency will Not Be reflected or observed Material does not absorb a certain frequency of light, that frequency Will Be reflected back All colors of light are reflected, white will be observed All colors of light are absorbed, black will be observed

Color The color we see depends on: The color of the light that is emitted on the object Color of light that is reflected by the object Color Filters allow only certain colors of light to be transmitted through them, they absorb or reflect all other colors Blue filter will only allow blue light to travel through Objects seen through a blue filter will be observed as blue Objects of other colors will appear black because the color wavelengths are being absorbed by the filter

Communication Using Waves 8.P.3A.6 Obtain and communicate information about how various instruments are used to extend human senses by transmitting and detecting waves (such as radio, television, cell phones, and wireless computer networks) to exemplify how technological advancements and designs meet human needs

Electromagnetic Spectrum Depicts the range of all possible frequencies of electromagnetic radiation Radio waves, low frequency, high wavelength energy waves Gamma rays, high frequency, low wavelength energy waves Which is more dangerous?

Signals Radio, Wireless computer networks, and wireless computer networks are examples of such technologies that benefit humans by receiving and transmitting signals through radio waves These signals are transmitted through a medium and captured by the device Air or fiber optic cables The higher the frequency, the more information it can carry Radio waves transmitted and received by wireless computer networkds are at higher frequencies than other devices Radio and televisions cannot detect these waves that carry the amounts of information required for internet usage

Signals sent and received by radios, televisions, cell phones, and wireless networks are often digitized (wave pulses) Digitizing is a more reliable way to send information When digitized, information can be recorded, stored for future recovery, and transmitted over long distances over long distances without substantial loss.