 Identify the crest, trough, amplitude, and wavelength of a wave  Define the terms frequency and period  Solve problems involving wave speed, frequency, and wavelength  Describe the Doppler effect

 Five main Properties that we are going to focus on:  Shape  Amplitude  Wavelength  Period  Frequency

 An ideal transverse wave has the shape of a sine curve  A sine curve looks like an S lying on its side  Sine curves can be used to represent the other properties of waves as well.

 Measures the amount of particle vibration  It is the greatest distance that particles are displaced from their normal resting positions because of the wave  It is also half the vertical difference between a crest and a trough › A crest is the highest point of the wave › A trough is the lowest point of the wave  Larger waves have bigger amplitudes and carry more energy

 Do not have crests and troughs because they cause particles to move back and forth instead of up and down  A longitudinal wave is like a spring  The areas where the coils are bunched together are called compressions  The stretched out areas are called rarefactions  The amplitude of a longitudinal wave is the maximum deviation from the normal density or pressure of the medium

 Wavelength is represent by the symbol lambda λ and is measured in meters  It measures the distance between two equivalent parts of a wave › In a transverse wave it’s the distance between two consecutive crests or two troughs › In a longitudinal wave it’s the distance between two consecutive compressions or two rarefactions › Sound waves have very complicated shapes and sometimes vibrate irregularly

 The time required for one full wavelength of a wave to pass by a certain point is called the period of the wave  It is also the time required for one complete vibration of a particle in a medium  It is represented by the symbol T and is measured in seconds

 Measures the rate of vibrations  It is the number of wavelengths that pass a point in a given time interval  It also measures how rapidly vibrations occur in the medium, at the source of the wave, or both  The symbol for frequency is f and it is measured in hertz (Hz)

 Named after Heinrich Hertz  In 1888, he became the first person to experimentally demonstrate the existence of electromagnetic waves  Hertz units measure the number of vibrations per second  One vibration per second is 1 Hz  You can hear sounds with frequencies as low as 20 Hz and as high as 20,000 Hz

 Elephants communicate with low-frequency sounds that humans cannot hear  Their low-frequency calls travel much further than higher-frequency sounds  Under the right conditions, an elephant call can carry over thirty square kilometers or more!  Elephant families separated by several kilometers use the calls to coordinate their movements  Other animals that communicate with low-frequency sounds include blue and finback whales, hippos, and rhinos.

 Frequency and period are related  Frequency is the inverse of the period  The following equation is used to calculate:

 Light comes in a wide range of frequencies and wavelengths  Our eyes can detect light with frequencies ranging from about 4.3 x Hz to 7.5 x Hz  Light in this range is called visible light.  The differences in frequency in visible light account for the different colors we see

 Electromagnetic waves also exist at other frequencies that we cannot see directly  The full range of light at different frequencies and wavelengths is called the electromagnetic spectrum

 Is equal to frequency times wavelength  It is simply how fast a wave moves  Wave speed is calculated using the following equations:

 An FM radio station broadcasts electromagnetic waves at a frequency of 94.5 MHz (9.45 × 10 7 Hz). These radio waves have a wavelength of 3.17 m. What is the speed of the waves?  f = 9.45 x 10 7 Hzλ = 3.17 m  v = ?  v = ƒ x λ  v = (9.45 x 10 7 Hz)(3.17m)  v = 3.00 x 10 8 m/s

 The speed of a wave depends on the medium  Sound waves travel fastest in solids, then in liquids and slowest in gases.  Temperature also affects wave speed.  Sound travels faster through hot air than cool air.

 Explains differences in wave speeds  The arrangement of particles in a medium determines how well waves travel through it  The different states of matter are due to different degrees of organization at the particle level

 In gases, the molecules are far apart and move around randomly.  In liquids, the molecules are much closer together. But they are also free to slide past one another  In a solid, molecules are not only closer together but also tightly bound to each other

 Light has a finite speed  The speed of light is 3.00 x 10 8 m/s  Since the speed of light through space is a constant it is often represent by the symbol c

 Is the apparent change in pitch as a sound passes by  The pitch of a sound is how high or low it is  Pitch is determined by the frequency at which sound waves strike the eardrum in your ear  A higher-pitched sound is caused by sound waves of higher frequency

 Suppose you could see the sound waves from the ambulance siren when the ambulance is at rest  You would see the sound waves traveling out from the siren in circular wave fronts  The distance between two successive wave fronts shows the wavelength of the sound waves  The sound waves have a frequency equal to the number of wave fronts that strike your eardrum each second  That frequency determines the pitch of the sound that you hear