Waves, Sound, and Light

1. Waves, Sound, and Light Chapter 3

2. Bell Work 11/29/10 Please get a new bell work sheet. Write each statement then decide if they are true or false, if false correct them. 1. Mechanical waves transfer energy through a vacuum. 2. A wave is a disturbance that transfers energy. 3. An example of a longitudinal wave is a water wave.

3. Light 3.1 Vocab Electromagnetic wave – a disturbance that transfers energy through a field Radiation – energy that moves in the form of EM waves

4. How EM waves form and sources of EM waves • Electric and magnetic fields make up EM waves • Many of the EM waves on Earth’s environment come from the Sun. • Stars give off EM waves but since they are so far away not many of their waves hit the Earth • Technology is also a source of EM waves

5. Bell Work 11/30/10 • What are the two types of fields that make up an EM wave? • How are EM waves used to measure distances in space? • How does microwave cooking depend on reflection?

6. Electromagnetic spectrum • The range of all EM frequencies • The spectrum goes from the lowest frequencies to the highest frequencies • Higher-frequency EM waves with more electromagnetic vibrations per second have more energy than lower-frequency EM waves

8. Measuring EM Waves • EM wave frequency is measured in hertz (Hz) • One hertz equals one cycle per second

9. Radio waves • Have the longest wavelengths, the lowest frequencies, and the lowest energies • Examples of radio waves are AM/FM radio and broadcast television

11. Microwaves • EM waves with shorter wavelengths, higher frequencies, and higher energy than other radio waves • Radar – radio detection and ranging. Used to control air traffic at airports, analyze weather conditions and measure the speed of a moving vehicle • Radar led to the invention of microwave ovens • Cell phones – radio transmitter and receiver that uses microwaves

13. Bell work 11/25/09 • List the colors of the visible light spectrum in order from longest wavelength to shortest wavelength. • What are the 7 parts of the electromagnetic spectrum?

14. Bell Work 11/30/09 Please use complete sentences • Give an example of using a radio wave. • Give an example of using a microwave. • Give an example of using an x-ray.

15. Bell Work 12/1/09 • What do electromagnetic waves transfer energy through? • What is radiation? • How does a microwave cook food?

16. Visible Light • The part of the EM spectrum that human eyes can see. • Longest wavelengths are red all the way to violet • ROY G BIV • Red, Orange, Yellow, Green, Blue, Indigo, Violet

17. Bell Work 12/2/09 • What are EM waves measured in? • Give two examples of using a radio wave. • Give 3 examples of using a microwave. • List the colors of visible light from longest wavelength to shortest wavelength.

18. Infrared Light • Type of EM wave most often associated with heat • Sometimes referred to as heat rays • You can feel it as warmth coming from the sun, a fire, or a radiator • Infrared lamps are used to provide warmth in bathrooms and to keep food warm after its been cooked • Some animals can see in infrared light

20. Ultraviolet Light • Has more energy than visible light • The waves in this range can damage your skin and eyes • Sun block and UV-protection sunglasses are designed to filter out the higher frequencies • UV light can be used to sterilize medical instruments and food by killing harmful bacteria • IV light causes skin cells to produce vitamin D which is essential to good health • UV light is visible to some animals. Bees and some other insects

22. X-rays • Has a very high frequency and energy • Pass easily through soft tissues of the body, but are absorbed by the bone • The x-rays pass through exposing the film where there is no bone • When getting x-rays other parts of the body are covered with a lead vest to block the x-rays

24. Gamma rays • Highest frequencies and energies of any EM waves • Produced by some radioactive substances as well as the sun and other stars • Gamma rays can penetrate the soft and the hard tissues of the body, killing normal cells and causing cancer cells to develop • Gamma rays can also be used to kill cancer cells and fight tumors

26. Bell Work 12/3/09 • Which group from the EM spectrum has the highest frequencies? • Which group pass easily through soft tissues of the body, but are absorbed by the bone? • What can you use to filter out the high frequencies of UV rays? • Which EM wave is most associated with heat?

27. Bell Work 12/4/09 Predict what would happen if you kept a green plant in the dark for one month. Explain why. (at least 3 sentences)

28. Vocab 3.3 Incandescence – the production of light by materials at high temperatures Luminescence – the production of light without the high temperature. Many organisms produce their own visible light through this.

29. Bioluminescence – production of light by living organism. These organism produce light from chemical reactions rather than intense heat. Fluorescence – occurs when a material absorbs EM radiation of one wavelength and gives off EM radiation of another.

30. Bell Work 12/5/09 • What happens to the speed of EM waves in a vacuum? • What happens when microwaves encounter water? • What produces the most EM waves on Earth?

31. Light 3.4 Notes Transmission – the passage of an EM wave through a medium. • If the light reflected from objects did not pass through the air, windows, or most of the eye, we could not see the objects

32. Absorption – the disappearance of an EM wave into the medium • Absorption affects how things look, because it limits the light available to be reflected or transmitted

33. How Materials Transmit Light • Transparent materials allow most of the light that strikes them to pass through. • Translucent materials transmit some light, but they also cause it to spread out in all directions. • Opaque materials do not allow any light to pass through them, because they reflect light, absorb light, or both

34. Scattering – the spreading out of light rays in all directions, because particles reflect and absorb the light • Fog or dust in the air, mud in water, and scratches or smudges on glass can all cause scattering • Scattering creates a glare and makes it hard to see even through a transparent material

35. Polarization – a quality of light in which all of its waves vibrate in the same direction • Polarizing filters reduce glare and make it easier to see objects Prism – a tool that uses refraction to spread out the different wavelengths that make up white light • Prisms split light into colors by refracting wavelengths in different amounts

36. Color Reflection and Absorption The color of an object or material is determined by two factors • the wavelengths it absorbs and those it reflects • The wavelengths present in the light that shines on the object

37. A material that reflects all wavelengths of visible light appears white • A material that absorbs all wavelengths of visible like appears black • A green lime absorbs most wavelengths but reflects green, so the lime looks green

38. Primary Colors of Light • The human eye can detect only 3 color bands: red, green, and blue • Your brain perceives these three colors and various mixtures of them as all the colors Primary colors – red, green, and blue – can be mixed to produce all the possible colors

39. Primary Pigments • Materials can be mixed to produce colors just as light can • Materials that are used to produce colors are called pigments Primary pigments – cyan, yellow, and magenta

40. Bell Work 12/8/09 • What color is something that absorbs all the colors? • What color is something that reflects all colors? • If an object absorbs most wavelengths but reflects violet what color will it be?

41. Bell Work 12/9/09 – (fill in the blanks) • Bioluminescent animals produce light through _________. • When light is absorbed into a medium, the waves ________ in the medium. • The primary pigments create colors through _____________ mixing. • An electromagnetic wave transfers energy through a ______. • Most of the visible EM waves on Earth come from the ______.