Waves PDF

Wave- a disturbance that carries energy through matter or spaces -​ Most waves travel through matter Medium- the matter through which waves travel ( wave in pond) ALL WAVES ARE EITHER MECHANICAL OR ELECTROMAGNETIC Mechanical- waves that require a medium to travel through (sound, earthquakes, tsun...

Wave- a disturbance that carries energy through matter or spaces -​ Most waves travel through matter Medium- the matter through which waves travel ( wave in pond) ALL WAVES ARE EITHER MECHANICAL OR ELECTROMAGNETIC Mechanical- waves that require a medium to travel through (sound, earthquakes, tsunamis) Electromagnetic waves- wave that do not require a medium- consist of interactions between electric and magnetic fields Energy is the ability to do work (bigger the waves- more energy) (smaller waves- less energy) -​ Energy spreads out as the wave travels -​ Mechanical waves spread out in circle from starting point (each circle is called a wave front- each circle carries the same total energy) -​ Sound waves travel in spheres Simple Harmonic Motion- A type of vibration where a force moves a mass back and forth in an effort to reach its original position Damped Harmonic Motion- type of vibration fades as energy is transferred from one object to another Transverse Waves- waves in which the wave motion is perpendicular to the particle of motion (electromagnetic waves) -​ Electric and magnetic fields are perpendicular to each other and direction of wave Crest- top of transverse wave Trough- Bottom of the transverse wave Longitudinal waves- wave where wave motion is parallel to the particle motion Compression- area where wave is crowded Rarefactions- area where wave is spread out Surface waves- waves in which the particles move both perpendicular and parallel -​ Occur at the boundary between two different mediums Amplitude- greatest distance that particles are displaced from their normal resting positions -​ Distance from rest to crest -​ Distance from rest to trough -​ Larger amplitude means wave carries more energy Wavelength- distance from crest to crest, trough to trough, or between two rarefactions or compressions -​ Represented by λ- lambda -​ SI unit is meters -​ Smaller wavelength means wave carries more energy Period - the time required for one complete vibration, time of one full wavelength -​ Represented by T -​ SI unit- seconds Frequency- the number of wavelengths in a period of time interval -​ Tells how fast vibrations occur in a medium -​ SI unit- Hertz (Hz)- number of vibrations per second -​ frequency= wave/ time Wave speed- distance a wave travels in a specific amount of time -​ distance/time -​ wavelength/ period -​ Wavelength x frequency -​ Wave Speed depends on the medium -​ All electromagnetic waves have finite speed -​ Speed of light is represented by C -​ Differences in frequency give us different colors Doppler effect- observed change in frequency due to motion between the source of waves and the observer -​ ex) and ambulance siren and a person walking by Reflection- bouncing back of waves when it meets a surface or boundary -​ Does not change wave speed or frequency -​ Can flip the wave upside down Defraction- bending of waves as they pass and edge of an obstacle or narrow opening -​ Depends on wavelength and size of barrier -​ When wave passes through edge of object, wave spreads out to create a new one Refraction- bending of waves passing from one medium to another -​ As waves change mediums, they change speeds too -​ ex) pencil looking broken in water - light passing through air to water creates bends Interference- combination of two or more waves that results in a different singular wave -​ Constructive interference- waves combine to make a bigger wave or louder sound -​ Destructive interference- waves are added together and make smaller wave or quieter sound Standing wave- pattern of vibration that simulates a wave standing still -​ Results from interference and reflection of wave -​ Nodes- points of total destructive interference- don't move -​ Antinodes- points of total constructive interference- move  Sound: -​ Sound waves are longitudinal waves and are also mechanical waves -​ Wavefronts for sound move in specific directions -​ Speed of sound depends on medium -​ Temperature impacts speed of sound- faster molecules (hotter) = faster sound travels Loudness- response to intensity of sound Intensity- rate at which sound waves transmits energy through medium Decibel scale(Db)- unit used to compare intensity of different sounds -​ Scale used to determine loudness of sounds -​ Based on logarithms- ten times louder than the last unit Pitch - measures how low or high sound is -​ depend s on frequency -​ Low frequencies= low pitch, high frequencies= high pitch Infrasound- frequency below what humans can hear Ultrasound- frequency above what humans can hear -​ Can travel through many materials- reflect back on material they hit Sonogram- using reflected sound waves to measure large distances Musical instruments:grouped based on vibrations -​ String instruments produce standing waves, changing wavelength (strings) changes frequency (pitch or sound) -​ Wind instruments produce standing waves in air columns- changing holes covered changes length of air column and changes pitch or sound -​ Membrane instruments produce standing waves on membrane Resonance- phenomenon occurs when two objects naturally vibrate at same frequency The Ear: catches sound and amplifies it -​ Outer ar catches sound causing eardrum to vibrate- vibrations are transferred to bones in inner ear and transfer from nerve cells to brain Light: has dual nature Light Wave: travels as transverse wave and electromagnetic wave Light Stream: stream of particles -​ Photons- packets or units of light, bundles of energy Electromagnetic spectrum- spectrum that consists of waves at all possible energies, frequencies, and wavelengths -​ Radio waves- tv signals, radio signals- radar is used to find locations of objects -​ Microwave- waves absorbed by food -​ Infrared- felt as warmth- measure change in atmosphere -​ Visible light- spans of small range of frequencies which determines color (ROYGBIV) -​ Ultraviolet- can be seen by insects- Ozone layer absorbs UV light - kills bacteria -​ Gamma Rays- used to kill cancer cells and take pictures of organs (high frequency) Light can pass through different materials- Transparent- transmit light allow most light to pass through (windows) Translucent- materials that scatter light and make the shape fuzzy Opaque- materials that totally absorb or reflect all light that strikes it Light Rays- an imaginary line running in directions that light travels through Geometrical optics- study of light in cases where light behaves like a ray Ray diagrams- geometrical drawings that trace the path of light Law of reflection- the angle of incidence Θ, equals the angle of reflection Θ𝑟 -​ Angle in= Angle out Regular reflection- all light rays are reflected as they go in -​ Smooth surfaces reflect light in one direction Diffuse reflection- all light rays are reflected in different angles -​ Rough surfaces reflect light in many different directions Mirrors: Mirrors reflect light based on law of reflection Image- a copy of an object formed by reflected or refracted light waves Flat mirror- produce upright images- same size as object Virtual images- images that result from apparent path of light rays, not an actual path (ALWAYS UPRIGHT) Convex mirrors- produce upright images smaller than original object (car mirrors) Concave mirrors- can produce upright images larger than original object When light is transmitted it can be…. Refracted- light bend when it passes into a new medium at an angle Polarized- light with waves that only has only one direction, unlike it normally does Scattered- light doesn’t come out the way it comes into a medium (sunrise, sunset) Lenses- a medium with a curved surface -​ Work due to refraction- the light bends Concave lenses- light rays diverge or spread apart- no images are visible only virtual images Convex lens- light rays will converge or come together -​ Convex lenses that produce virtual images can be used for magnification The eye: You see because you have a lens behind your pupil in your eye- image appears on the retina which is in the back of the eye- your eye sees a real image ich is upside down and the brain flips it right side up Prisms- an object that can separate white light into its component colors -​ As light enters prism, wave speed changes creating different colors through refraction -​ Red traves fasts and bends the least - violet travels the slowest and bends the most Dispersion- effect in which light separates into different colors because of differences in speed Color- color depends on the frequency of visible light that reaches your eye -​ White light contains all colors - black light is the absence of color where all light waves are absorbed Additive primary colors of light- red, blue, and green Subtractive primary colors- yellow, cyan, magenta red+green= yellow blue +red= magenta green+blue= cyan Complementary colors- two colors that combine to make white -​ red+cyan= white -​ blue+yellow=white -​ green+magenta= white light