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Characteristics of Waves

Characteristics of Waves. What are waves?. Wave – a disturbance that transfers energy from place to place . Wave pulse – A single bump or disturbance that travels through a medium Periodic Wave – A wave that moves up and down at the same rate.

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Characteristics of Waves

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  1. Characteristics of Waves

  2. What are waves? • Wave– a disturbance that transfers energy from place to place. • Wave pulse – A single bump or disturbance that travels through a medium • Periodic Wave – A wave that moves up and down at the same rate. • Medium– the material thru which a wave passes • Waves travel trough the medium without actually moving the medium with it.

  3. Wave Particle Movement Transverse Waves Compression Wave Waves travel trough the medium without actually moving the medium with it. Basically the medium stays put while the wave moves some distance

  4. Types of Waves: Transverse Waves: waves that move the medium at right angles to the direction in which the waves are traveling. Longitudinal Waves: move particles parallel to the direction the wave is moving, “push-pull” waves. Surface Waves: have properties of both transverse and longitudinal waves

  5. Measuring Waves Longitudinal Wave

  6. Measuring Waves Transverse Wave

  7. Properties of Waves Speed – distance the wave moves divided by time. In most mechanical waves, the speed only depends on the medium through which the wave is traveling Amplitude– in a transverse wave – the height away from the “rest” position. The amplitude in a longitudinal wave is the measure of how compressed or rarefied the medium becomes. Wavelength– the distance between two corresponding parts of a wave. Frequency– the number of complete waves that pass a given point in a certain period of time. Frequency is measured in HERTZ, one Hz is a wave that occurs once every second.

  8. Measuring Waves Phase= any two points on a wave that are one or more whole wavelengths apart are in phase Period (T)=the amount of time required for an object to repeat on complete cycle of motion Frequency (f)= the number of complete oscillations that a wave makes each second, measured in Hertz (Hz)

  9. EQUATIONS!!!!! • Frequency of a Wave: • f=1/T • Frequency is equal to the reciprocal of the period • Measured in Hertz (Hz) • Wavelength : λ=v/f • Wavelength is equal to the velocity divided by the frequency • Measured in meters (m)

  10. Speed Frequency & Wavelength S = x f = 1.5 m x 280 Hz = 420 m/s S = S / f = 5.0 m/s / 2.5 Hz = 2 m x • Speed (meters/sec)= wavelength x frequency • Frequency (Hz = 1/sec)= speed / Wavelength • Wavelength (meters) = speed / Frequency • Designated by Greek letter lambda -

  11. Practice Problem • A sound wave has a frequency of 192 Hz and travels the length of a football field, 91.4m, in 0.271 s. • What is the speed of the wave? • What is the wavelength of the wave? • What is the period of the wave? • If the frequency was changed to 442 Hz, what would be the new wavelength and period? • ANS: • v=337m/s • λ= 1.76m • T=.00521 s

  12. Interactions of Waves • Refraction– The bending of a wave due to the wave moving from one type of medium into another. • Reflection– Bounce back wave • Angle of Incidence is the angle of the wave coming into the object reflecting the wave. • Angle of Reflection is the angle bouncing off and going away from the object.

  13. Interactions of Waves Diffraction– Wave passing a barrier or going through a hole in a barrier bends and causes the wave to wrap around the barrier

  14. Superposition of Waves Principle of superposition= the displacement caused by two or more waves is the algebraic sum of the displacements caused by the individual waves Translation= two or more waves can combine to form a new wave Interference= the result of the superposition of two or more waves

  15. Interactions of Waves • Interference – when two or more waves meet, they interact. This interaction is called interference. • 1. Constructive Interference – the combining of waves to cause higher amplitude of any of the original waves. • 2. Destructive Interference – when the combining of the waves produce a new wave with a smaller amplitude than the beginning waves

  16. Standing Waves Standing Waves – the combining of the incoming and reflected wave so that the resultant appears to be standing still Node– the point where Constructive Interference and Destructive Interference cause an amplitude of zero on the standing wave. Antinode– the point where Constructive Interference and Destructive Interference of a standing wave are represented by the crest and the trough. Resonance– the point where vibrations traveling thru and object matches the natural vibrations of an object. I.e. an opera singer hitting a note and shattering a crystal glass.

  17. Seismic Waves • Seismic Waves – waves caused by the release of energy due to earthquakes composed of • P - primary waves • S - secondary waves • L - surface waves

  18. P Waves P waves –- Primary waves are pressure waves & are the fastest moving waves, they travel thru solids and liquids, Push-Pull Waves AKA Longitudinal waves

  19. S Waves S Waves – Secondary Waves are slower than primary waves, they cannot travel thru liquid and are Transverse Waves.

  20. L Waves • L Waves (last waves) Surface wave – the combination on the Earth’s surface of Primary and Secondary waves. • The rolling chaotic movement of the surface • Cause the most damage of the seismic waves

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