1. Waves

2. Examples –Water waves –Sound waves –Light waves –Radio waves –microwaves

3. Waves are everywhere Part of everyday life Waves carry oscillations from one place to another –earthquakes Waves carry information and energy

4. Types of waves Transverse –Oscillations perpendicular to direction the wave moves –Oscillates up and down –Wave moves left to right

6. Longitudinal wave –Oscillations in same direction of wave movement –Compressions –rarefactions

8. Basic Properties Frequency- how often wave goes up and down –Measured in hertz Amplitude- max distance above the level surface

9. Wavelength- length of one complete cycle of a wave –Crest to crest or trough to trough –lambda

10. Speed- how fast the wave transmits an oscillation –Water- few mph –Light- 186,000 mph –Sound- 660 mph

11. Speed of wave is NOT up-down speed of surface To measure speed, start ripple and measure how long it takes to affect a distant place

12. Speed of wave = wavelength x frequency

13. Wave shapes Crests Troughs Plane waves Circular waves

14. Plane wave

15. Circular wave

16. Wave interactions Reflection- bounce off and go in new direction

17. Refraction- wave passes into and through obstacle

18. Diffraction- Wave bends around or through holes in obstacle

19. Absorption- wave absorbed and disappears

20. Sound

21. Ear

22. How do we hear? 1.Eardrum vibrates as sound waves enter ear canal 2.3 bones of inner ear -hammer (malleus), anvil (incus), stirrup (stapes) transmit vibrations to cochlea

23. 3. Cochlea- fluid filled organ responsible for hearing as well as balance- fluid vibrates and creates waves that travel up spiral and stimulate tiny hairs (receptor cells) –Nerves near large end respond to longer wavelengths, lower frequencies –Nerves near narrow end respond to shorter wavelengths, higher frequencies

25. Human Hearing Range of human hearing (20-20,000 Hz) Hearing ability changes with people and age

26. Hearing can be damaged by loud noise Tiny hairs in cochlea will weaken or break

27. Ultrasound Greater than 100,000 Hz- passes through human body easily Refractions and reflections inside body used to create images.

28. Properties of Sound Air - molecules in constant random motion –Air pressure Anything that vibrates produces sound waves as long as there is air or other material

29. Longitudinal wave

32. Loudness of Sound Decibel scale (dB)- related to amplitude

33. For every increase of 20 dB = 10 times greater amplitude Ears are very sensitive- detect differences in sound waves that are 2 parts out of 100 million!= EASILY DAMAGED