Light and Sound

1. Light and Sound

2. Sound Waves • Caused by vibrations • Move in all directions from the source of the sound

3. Speed of Sound • Does speed travel faster in solids, liquids or gases? And why?

4. Speed of sound and light • Which travels faster sound or light?

5. Doppler Effect • Why does the siren have a higher pitch sound when it approaches you? • What is the relationship between pitch and frequency?

7. Speed of Sound • Does speed travel faster in solids, liquids or gases? *Western movies

8. Speed Depends on Medium • Travels better in more dense objects (generally) • Temperature also affects how well it travels

9. Speed of sound and light • Which travels faster sound or light?

10. Speed of waves • Speed of sound in air is 330 m/s • Speed of light is 3 x 108 m/s

11. Doppler Effect • Why does the siren have a higher pitch sound when it approaches you? • Explain in terms of frequency • What is the relationship between pitch and frequency?

12. Pitch • How high or low a sound sounds • Relates to the frequency of a sound • Humans can hear from 20 to 20,000 Hz

13. Infra and Ultra • Infrasounds are those with frequencies lower than 20 Hz • Ultrasounds are those with frequencies higher than 20000 Hz

14. Compressions • Points in a longitudinal wave where the wave is compressed • Rarefactions are places where the wave is spread

15. Rates of Vibrations

16. Loudness Is Determined by Intensity • When a vibration is more intense it will make a louder sound due to the greater vibration of your eardrum http://www.eoascientific.com/interactive/light_radio_sound_waves/light_radio_sound_waves.html

17. Relative Sound Intensity • The decibel scale compares sound to other sounds • A sound seems twice as loud when the intensity is ten times as great

18. Harmonics http://illuminations.nctm.org/mathlets/soundwave/ • Different musical instruments have different sound qualities depending on the different waves formed in the instrument

19. Music

20. Resonance • This occurs when a vibration from object causes another object to vibrate at a natural frequency

21. The Ear • Sound strikes the eardrum • Causes the inner ear bones to vibrate against the cochlea

22. The Ear • The basilar membrane vibrates at different frequencies sending info to the brain

23. Sonar • Boats and subs use sonar to measure distance by how long it takes a sound to bounce back

24. Ultrasound Imaging • Doctors often look at babies using ultrasound • They can also use it to detect abnormal body conditions

25. Photoelectric Effect • Light causes electrons to be lost from metal • Not consistent with the wave theory

26. Interference • Light can be shown to have interference patterns like sound • This is consistent with a wave type light

27. Wave Particle Duality • Light can be seen as a wave like sound or as a particle • This is called wave particle duality

28. Photons • “Particles” of light are called photons • The energy of a photon is proportional to the wavelength and frequency

29. Medium • Light does not need one • The speed of light is dependent on the medium, however

30. Intensity • This is the rate at which light or any other form of energy flows through a given area of space

31. EM Spectrum • Light is a range of the EM spectrum from 400nm to 700 nm • Red light has longer waves and violet shorter

32. Ultraviolet • Just shorter λ than visible light • Ozone protects the earth from this energy

33. X-rays and Gamma Rays • X-rays are useful for diagnosis • Gamma rays are useful for treating cancer

34. Infrared • Used for heat lamps and IR goggles • Also used in some photography equipment

35. Microwaves • Used for ovens and telecommuni-cations

36. Radio Waves • Used for radio transmission, radar, and for long range telescopes

37. Light Rays • Imaginary models of light waves called light rays are often used to study the behavior of light

38. Reflected Light • Rough surfaces reflect light in many directions • Smooth surfaces reflect light in one direction

39. Angle of Incidence • When light is reflected from a smooth surface the angle or incidence is equal to the angle of reflection

40. Flat Mirrors • Produce a virtual image, or one that cannot be projected • The image is also inverted

41. Convex Mirrors http://www.olympusmicro.com/primer/java/mirrors/convexmirrors/index.html • These are mirrors that bulge out in the center • Make an image that is stretched out

42. Concave Mirrors http://www.olympusmicro.com/primer/java/mirrors/concavemirrors3d/index.html • Make a real image or one that can be projected

43. Color • Objects that are colored reflect light at certain wavelengths • This makes them appear a certain color

44. Color Cont. http://www.olympusmicro.com/primer/java/filters/gelatin/index.html • A rose in white light looks red and green • A rose in red light looks only red • P. 410

45. Additive Colors • These colors (red, green, and blue) add to make white light • These are the colors in a TV

46. Subtractive Colors • Yellow, cyan, and magenta combine to make black • Printer inks are these colors

47. Refraction • This occurs when light changes media • Lenses and prisms make this occur

48. Refraction Cont. • Makes objects appear to be in different positions depending on the angle of refraction

49. Total Internal Reflection • The complete reflection of light at the boundary between two mediums • Used for fiber optics

50. Lenses • Rely on refraction to change the direction of light rays that pass through