2 What is a Wave? Examples of Waves: Wave: A disturbance that carries energy through matter or space.Examples of Waves:Sound you hear from your headphonesEarthquakesRipples in a pond
3 MediumsA wave is not made of matter, but involves the movement of matter.Most waves travel through a medium.Medium: the matter through which a wave travels.Examples:Sound you hear from your headphones: AirEarthquakes: EarthRipples in a pond: Water
4 Types of Waves Mechanical Waves: Most waves are mechanical waves They require a medium (like water or air) to travel through.
5 Types of Waves Electromagnetic Waves: Do NOT require a medium to travel throughMade of changing electric and magnetic fields, which radiate at the speed of light (3x108m/s)This shows the wave traveling along one line, but it actually fills space.
6 Electromagnetic Waves Anything that is part of the electromagnetic spectrum is an electromagnetic wave. That includes:Radio wavesMicrowavesInfraredVisible lightUltraviolet lightX-RaysGamma Rays
7 Types of WavesMechanical WavesElectromagnetic Waves
8 Waves do WorkWe know that waves carry energy because they can do work:Examples:Water waves can do work on a leaf or a boatSound waves can do work on your eardrum
9 Waves do Work The larger the wave, the more energy it carries. Example:A cruise ship moving through the ocean may create waves big enough to move a fishing boat up and down a few meters.
10 Characteristics of Waves If you go to a rock concert and stand next to the speakers, the sound waves may damage your ears. But if you stand 100 m away, the sound of the rock band is harmless. Why?As waves travel outward, the spherical wave fronts get bigger, so the energy spreads out over a larger area.
11 Transverse and Longitudinal Waves Waves are classified according to the direction in which particles in the medium move as a wave passes by; they can either move up and down or back and forth.They are classified as either transverse or longitudinal.
12 Transverse WavesTransverse wave: wave in which wave motion is perpendicular (up and down) to particle motion.Examples:A crowd doing “the wave”; individual people move up and down, but the motion travels around the stadiumElectromagnetic waves; electric and magnetic fields are perpendicular to each other
13 Motion of particles in a transverse wave Wave travels to the right:Particle motionWave motion
14 Longitudinal Waves (Compression Wave) Longitudinal waves: Waves in which wave motion is parallel to the particle motion.Example: Sound waves; as they move through the air, molecules in the air move backward and forward, parallel to the direction the sound waves travel.
15 Parts of Waves Transverse Waves Longitudinal Waves Crests: high points of transverse wavesTroughs: low points of transverse wavesCompressions: crowded areas of longitudinal wavesRarefactions: stretched out areas of longitudinal waves
16 Surface Waves Some waves are not simply transverse or longitudinal: Surface Waves: Waves that move both perpendicular and parallel to the direction of wave motion.Example: Waves on the ocean or swimming poolThis type of wave also occurs at the boundary between 2 different mediums, like water and air.