Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives 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. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer There are many different types of waves. You may be familiar with the electromagnetic spectrum, which includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X rays, and gamma rays. 1.Name five common applications of waves in the electromagnetic spectrum, and list the type of wave used in each case. 2.Lasers are made from accurately focused visible light waves that are produced in phase with each other. Lasers made from visible light waves are often used in surgery to perform delicate procedures and to seal the area being treated. Write a paragraph describing how you think this process works. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties An ideal transverse wave has the shape of a sine curve. Section 2 Characteristics of Waves Chapter 14 Waves that have the shape of a sine curve are called sine waves.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties, continued Amplitude measures the amount of particle vibration. The crest is the highest point of a transverse wave. The trough is the lowest point of a transverse wave. The amplitude is the maximum distance that the particles of a wave’s medium vibrate from their rest position. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Characteristics of a Wave Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties, continued A longitudinal wave has compressions and rarefactions. The crowded areas 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. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu A. A longitudinal wave has compressions and rarefactions. B. The high and low points of this sine curve correspond to compressions and rarefactions in the spring. Section 2 Characteristics of Waves Chapter 14 Wave Properties, continued

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties, continued Wavelength measures the distance between two equivalent parts of a wave. The wavelength is the distance from any point on a wave to an identical point on the next wave. Not all waves have a single wavelength that is easy to measure. Wavelength is represented by the Greek letter lambda,. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties, continued The period measures how long it takes for waves to pass by. The period is the time that it takes a complete cycle or wave oscillation to occur. The period is represented by the symbol T. Frequency measures the rate of vibrations. The frequency is the number of cycles or vibrations per unit of time. The symbol for frequency is f. The SI unit for measuring frequency is hertz. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Characteristics of Waves Frequency Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Period of Ocean Waves Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties, continued The frequency and period of a wave are related. The frequency is the inverse of the period. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Properties, continued Light comes in a wide range of frequencies and wavelengths. Our eyes can detect light with frequencies ranging from about 4.3  Hz to 7.5  Hz. Light in this range is called visible light. The full range of light at different frequencies and wavelengths is called the electromagnetic spectrum. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visible Light Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Electromagnetic Spectrum Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Speed Wave speed equals frequency times wavelength. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Equation for the Speed of a Wave Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Math Skills Wave Speed The string of a piano that produces the note middle C vibrates with a frequency of 264 Hz. If the sound waves produced by this string have a wavelength in air of 1.30 m, what is the speed of sound in air? 1.List the given and unknown values. Given: frequency, f = 264 Hz wavelength, = 1.30 m Unknown: wave speed,  = ? m/s Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2.Write the equation for wave speed.  = f  3.Insert the known values into the equation, and solve.  = 264 Hz  1.30 m = 264 s −1  1.30 m  = 343 m/s Math Skills, continued Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Speed, continued The speed of a wave depends on the medium. In a given medium, though, the speed of waves is constant; it does not depend on the frequency of the wave. Kinetic theory explains differences in wave speed. The arrangement of particles in a medium determines how well waves travel through it. In gases, the molecules are far apart and move around randomly. Waves don’t travel as fast in gases. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Wave Speed, continued In liquids, such as water, 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. Waves travel very quickly through most solids. Light has a finite speed. All electromagnetic waves in empty space travel at the same speed, the speed of light, which is 3.00  10 8 m/s ( mi/s). Section 2 Characteristics of Waves Chapter 14 Light travels slower when it has to pass through a medium such as air or water.

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Doppler Effect Pitch is determined by the frequency of sound waves. The pitch of a sound, how high or low it is, 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. Frequency changes when the source of waves is moving. The Doppler effect is an observed change in the frequency of a wave when the source or observer is moving. Section 2 Characteristics of Waves Chapter 14

Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Doppler Effect and Sound Section 2 Characteristics of Waves Chapter 14