Properties of Waves

1. Properties of Waves By Lisa Mahon and Michael Jakab

3. Click to Go Back to Table of Contents Waves • Moving energy, disturbances moving through, over or under the medium • Can move across ropes, strings, or any surface of water & some through space • When moving, they cause wave disturbances which are symmetrical, or regular, wave patterns • Water waves move the water units up and down on the spot don't move any water along the wave, the energy travels and does it

4. Different Waves • Sound • Listening to radio • Light • Eyes to computer screen • Radiation • X-rays • Ropes • Hold a rope and attach it to motionless object, flick it up and down • Air • Someone taking on their cell phone, transmission air waves • Water • Ocean waves

5. Types Of Waves • Longitudinal • Move in the same direction as the transfer of energy • Parallel to energy movement • Also known as compression wave • Compression=region where coils are pushed together in a limited amount of space • Example: Slinky, pulling it back end vibrating in horizontal direction • Transverse • Particles vibrate at right angles to the force of energy movement • Displaced in perpendicular direction of the movement of energy • Example: rope stretched horizontally, end vibrating back and forth in vertical actions

6. equilibrium line

7. Wavelength & Period • Wavelength • Distance from any point on a wave to the same point on the next circle • Length of one complete wave cycle • Horizontal distance across the wave between similar points • Represented by l • Period • Recurrence at equal intervals of times • represented as T • Distance from one crest to the next • Speed= wavelength/period

8. Frequency • The number of wave cycles that passes in a given amount of time • Measured in hertz (Hz) • 1 Hz = 1 wave per second • F= frequency

9. Amplitude & Cycle • Amplitude • Height of the wave from the equilibrium to a peak • Maximum displacement of a wave • “distance from rest to crest” • Cycle • One wavelength= one complete cycle • Series of repeated wave changes

10. Crests & Troughs • Crests • Maximum amount from the displacement of the rest point in a positive, or upward, direction • Troughs • the wave point that is the maximum amount of the negation, or downward, displacement on from equilibrium • Amplitude is below average value

11. Wave Equations • Velocity= f x l • Frequency= 1/T (t = period) • Velocity= l/f • l= v/f • Frequency= l/v Key: F- frequency T- period V-velocity l- wavelength

12. Examples of Equations • What is the period of a wave that has a wavelength of 1 meter and a speed of 20 m/s? • .05 sec • Equations used: velocity= frequency x wavelength ; frequency= 1/period • If the frequency of a wave is 30 hertz, how many wavelengths pass a certain point in 30 seconds?’ • 900 waves • Equation used: speed- frequency x wavelength • A sound wave has a speed of 400 m/s and a frequency of 200 Hz. What is the wavelength? • Wavelength= 2m • Equation used: wavelength- speed/ frequency Look Back On equations from previous slide..click here!

13. Harmonic Waveform

14. Diagram crest Wavelength (one) period amplitude Equilibrium line trough

15. Wave Speed & Velocity • Basic speed wave equations • Velocity= speed • Wavelength/period • Frequency x wavelength • Wave Speeds • Fast: light waves • Medium: sound waves • Slow: water waves

16. References • http://dictionary.reference.com • http://www.s-cool.co.uk/gcse/physics/properties-of-waves/revise-it/describing-waves • http://www.physicsclassroom.com/class/waves/U10L2a.cfm • http://www.absorblearning.com/physics/demo/units/DJFPh063.html • http://stumphengedesign.com/poleshft1c.htm • Stanford notes • http://www.a-levelphysicstutor.com/wav-wave-props.php

17. Quiz • 1.) Where can waves move? • a.) water • b.) rocks • c.) clay • 2.) Name 2 different types of waves ________&________ • 3.) Particles vibrate at right angles are called _________ • 4.) Distance from any point on a wave to the same point on the next circle is called a(n)___________

18. Quiz • Match the correct symbol with the word. • 5.) Frequency a.) l/f • 6.) Wavelength b.) T • 7) Velocity c.)hertz • 8.)Period d.) l 9.) What is the difference between a Crest and aTroughs? 10.) Match the following to the correct statement Lightwaves slow Sound waves medium Water waves fast 11.)Longitudinal waves move in what direction?

19. Quiz • 12.) What is the period of a wave that has a wavelength of 1 meter and a speed of 20 m/s? • 13.) If the frequency of a wave is 30 hertz, how many wavelengths pass a certain point in 30 seconds?’ 14.) A sound wave has a speed of 400 m/s and a frequency of 200 Hz. What is the wavelength? 15.) What is the distance from one wave to another called?_________

20. Quiz Answers • 1.) A • 2.) sound, radio, light, radiation, x-rays, ropes • 3.) Transverse • 4.) wavelength • 5.) C • 6.) D • 7.) A • 8.) B • 9.) A crest is maximum amount from the displacement of the rest point in a positive, or upward, direction. A trough is the wave point that is the maximum amount of the negation, or downward, displacement on from equilibrium. • 10.) Fast: light waves Medium: sound waves Slow: water waves

21. Quiz Answers • 11.) in the same direction as the transfer of energy • 12.) .05 sec • 13.) 900 waves • 14.) 2m • 15.) wavelength