Chapter 11 Waves

Waves wave – a rhythmic disturbance or movement that transfers energy through matter or space examples: ocean waves disturb the water and transfer energy through it light waves travel through empty space to transfer energy from one place to another

Waves

Waves wave – a rhythmic disturbance or movement that transfers energy through matter or space examples: ocean waves disturb the water and transfer energy through it light waves travel through empty space to transfer energy from one place to another waves will exist only as long as it has energy to carry all waves are created by vibrations

Waves medium – any material through which an energy wave is transferred the medium for sounds waves is air the medium for ocean waves is water

Waves Mechanical Waves – waves that can only travel through matter Types of Mechanical waves transverse wave - a type of wave where the matter in the medium moves back and forth at right angles to the direction that the wave travels

Waves Transverse Waves

Waves Mechanical Waves – waves that can only travel through matter Types of Mechanical waves transverse wave - a type of wave where the matter in the medium moves back and forth at right angles to the direction that the wave travels these waves have crests (highest point) and troughs (lowest points)

Waves Transverse Waves

Waves Types of Mechanical waves compressional wave - a type of wave where the matter in the medium moves back and forth in the same direction that the wave travels similar in movement to the compression and expansion of a spring

Waves compressional wave - a type of wave where the matter in the medium moves back and forth in the same direction that the wave travels similar in movement to the compression and expansion of a spring example: sound waves occur when air molecules are pushed together when a surface is hit and that sound is carried through compressions and expansions of the wave through air causes the eardrum to vibrate when it reaches the eardrum

Waves Compressional Wave

Waves Parts of a Transverse Wave crest – the highest points of the wave trough – the lowest points of the wave

Waves Parts of a Compressional Wave compression – the denser (or more compressed) region of the wave example: where the coils are close together rarefaction – less dense (or more stretched) region of the wave example: where the coils are more spread out

Waves Compressional Wave

Waves Common Parts of Waves wavelength – distance between one point on a wave and the nearest point just like it measured in meters (m) represented with the Greek letter lambda λ

Waves Common Parts of Waves frequency (f) – the number of wavelengths that pass a fixed point each second measured in hertz (Hz = 1/s)

Waves Wave Velocity (v) – describes how fast a wave is traveling measured in meters per second (m/s) example: v = 300,000,000 m/s for most electromagnetic waves in a vacuum

Waves Calculating Velocities of Waves the speed of a wave depends on the medium through which it is traveling sound waves usually travel faster in liquids and solids than they do in gases light waves and other electromagnetic waves usually travel faster in gases or a vacuum than they do in solids and liquids

v =   f Waves Formula for calculating the velocity of a wave: v: velocity (in m/s) : wavelength (in m) f: frequency (in Hz or 1/s) v =   f

Waves What is the speed of a wave with a wavelength of 2 m and a frequency of 3 Hz? v =   f

Waves A wave is traveling at a velocity of 12 m/s and its wavelength is 3 m. Calculate the wave frequency. v =   f

Waves amplitude – a measure of the energy carried by a wave Transverse Waves the taller the wave, the more energy it has the shorter the wave, the less energy it has

Waves amplitude – a measure of the energy carried by a wave Compressional Waves the more dense the wave, the more energy it has the less dense the wave, the less energy it has

Waves Compressional Waves