WAVES A wave is a repeating disturbance or

WAVES A wave is a repeating disturbance or movement that transfers energy through matter or space.

Examples of Waves • Ocean waves disturb the water and transfer energy through it. • Energy is transferred through the Earth in powerful waves during an earthquake. • Light waves travel through space transferring energy from the Sun to the Earth.

Waves transfer energy. Energy can be defined as doing work. For example • Sound waves do work on your eardrums • Light waves do work on your eyes or on film. • Water waves do work on boats and the beach.

The matter that waves travel through is called a medium. • Mediums may be solid, liquid, or gas. • Light and radio waves don’t need a medium. They can travel through space. • Light waves are also called electromagnetic waves.

Waves that can only travel through matter are called mechanical waves. Transverse waves Compressional waves �Matter in the medium moves back and forth perpendicular to the direction that the wave travels. �Matter moves back and forth along the same direction that the wave travels. Sometimes called longitudinal waves.

Examples of each… Transverse Waves �Electromagnetic � Light Compressional Waves �Sound �Slinky � Radio � UV � X-Rays � Microwaves �Doing the wave Seismic and ocean waves are a combination of transverse and compressional because matter is pushed up and down as well as back and forth.

Seismic Waves � P Waves� Primary waves � Travel faster � Arrive at a location sooner � Compressional-shake ground side to side �S Waves � Secondary waves � Move slower but carry more energy � Transverse waves-shake ground up and down causing a lot of damage

Answer the following questions on a separate sheet of paper. �What type of waves do you see or encounter on a daily basis? �Explain the difference between transverse and compressional waves. �Since waves transfer energy, what are some practical uses for that energy? �Identify the medium for each wave. �Ripples on a pond �Sound waves from a speaker �Seismic waves

Parts of a wave

Time period

Speed and Frequency

Wave Properties Vocab � Wavelength- the distance between any tow successive identical parts of a wave. � Crest- the highest point of a transverse wave � Trough- the lowest point of a transverse wave � Amplitude-the greatest distance that particles in a medium move from their normal position when a wave passes. � Period-the time required for one full wavelength to pass a certain point. � Wave Speed- the speed at which a wave passes through a medium (v) � Wave speed= frequency x wavelength OR � Speed= wavelength / period � Frequency- the number of vibrations that occur in 1 second. (f) � frequency=wave speed / wavelength

v. The speed of a wave depends on the medium it is traveling through. v. Wave speed is measured in m/s. v. Sound waves travel faster through liquids and solids because the particles in solids are close together and they bump into each other more often than in gas v. For example, the speed of sound is 340 m/s v. Light waves travel faster in gas or empty space. v. For example the speed of light is 3 x 10 or 186, 000 mi/s. 8 Wave Speed

Frequency • The wavelength of a wave decreases as the frequency increases. • Remember, frequency is the number of vibrations that occur in one second.

Compressional Waves

One last slide just FYI… � The ear consists of three basic parts the outer ear, the middle ear, and the inner ear. Each part of the ear serves a specific purpose in the task of detecting and interpreting sound. The outer ear serves to collect and channel sound to the middle ear. The middle ear serves to transform the energy of a sound wave into the internal vibrations of the bone structure of the middle ear and ultimately transform these vibrations into a compressional wave in the inner ear. The inner ear serves to transform the energy of a compressional wave within the inner ear fluid into nerve impulses that can be transmitted to the brain. The three parts of the ear are shown below.

Wave Interactions �Reflection- the bouncing back of a wave as it meets a surface or boundary �Diffraction- the bending of a wave as it passes an edge or an opening �Refraction-the bending of waves as they pass from one medium to another �Interference- the combination of two or more waves that exist in the same place at the same time �Constructive- interference resulting in waves combining to make larger wave �Destructive- interference resulting in waves combing to make smaller wave �Standing Wave