1. Light!

2. a form of radiation emitted by stars and other celestial bodies consists of changing electric and magnetic fields can travel through empty space What is light?

3. Light is the only part of the electromagnetic spectrum that we can see. It is between infrared (heat) and (ultraviolet).

4. Wave Model Energy travels in the form of a wave at 300,000 km (186,282 miles) per second. This is the speed of light!

5. Wavelength The size of a wave is called wavelength. Wavelength is measured from the crest of a wave to the crest of the next wave. The more energy there is, the skinnier the waves become.

6. Frequency the number of waves that pass in a unit of time How “frequently” does a wave pass? determined by counting the waves (count from crest to crest)

7. Wavelength and Frequency all waves travel at the same speed wavelengths are measured crest to crest long wave → low frequency short wave → high frequency

8. Wavelength and Frequency Blue light has more energy. Blue waves are smaller and there are more of them.

9. Photon Model Light is made of particles or bundles of energy that travel in a beam or stream.

10. Ray Model A light ray is an imaginary line running in the direction that light travels.

11. The three models are all used as each helps to explain some of the properties of light energy.

13. White light comes from the Sun.

14. Roy G. Biv White light contains all of the wavelengths of visible light.

15. Roy G. Biv – longest to shortest wavelength

16. What is color? Why is this shirt red?

17. What is color? Object have color because they reflect light. A red shirt is red because it absorbs ALL of the colors EXCEPT red. The red wavelengths are reflected.

18. What is color? What makes white? What makes black?

19. What is color? A white shirt is white because it reflects ALL of the wavelengths of light. A black shirt is black because it absorbs ALL of the wavelengths of light. NONE are reflected. Why do you wear light colors in the summer and avoid darker ones?

20. Which color is easiest to see?

21. NASA used pink dye in Apollo but now the Navy uses green phosphorescent dye.

22. Fluorescence + Phosphoresence Explained using the photon model. Excited electrons jump up to a higher energy level. When they fall back down, the extra energy is given off as light.

23. A prism separates light into a rainbow.

24. A raindrop creates a rainbow.

25. When different colors are combined, white light is created.

26. How do the screens of electronic devices work? Combine red, green, blue to get yellow, cyan and magenta. Turning off all of the colors creates black. Combining them creates white. https://video.search.yahoo.com/yhs/search;_ylt=A0LEVvNRmtNUWz sALNknnIlQ;_ylu=X3oDMTB0ZjNuMHJ1BHNlYwNzYwRjb2xvA2JmM QR2dGlkA1lIUzAwM18x?p=mystery+of+magenta&hspart=mozilla&hs imp=yhs-001

27. Light Spectra Continuous Spectra – solids, liquids and dense gases emit light at all wavelengths when heated Emission Spectra – lines created when electrons drop down energy levels and release photons Absorption Spectra – occurs when a cold, dilute gas emits light, creating black lines for the energy absorbed

28. Visible Light Spectra Notice that a continuous spectrum has no breaks and that the emission and absorption spectra are mirror images.

29. Spectroscope

31. Hydrogen and Helium We know that the sun is made of hydrogen and helium because we see these spectra when we use a spectroscope.

32. Fiber Optic Technology

33. Nanowires 1/1000 the diameter of a human hair too small to contain a wavelength of light light travels along the wire (analogous to a train riding on tracks) can be used to BEND light! could make smaller and faster computer processors

34. Bose Einstein Condensates Velocity-distribution data (3 views) for a gas of rubidium atoms, confirming the discovery of a new phase of matter, the Bose–Einstein condensate. Left: just before the appearance of a Bose–Einstein condensate. Center: just after the appearance of the condensate. Right: after further evaporation, leaving a sample of nearly pure condensate. Recently discovered to be able to stop light!

35. Last year, a team of Scottish scientists made light travel slower than the speed of light! Photons were sent through a special mask that changed the shape of the photon, causing it to slow down. The photons remained at the lower speed even when the returned to free space. The photons exhibit “wave-particle duality” in that they behave both like a wave and a particle. There is no application for this discovery as yet. Peloton – The main bunch of riders moves at a constant speed but within the bunch, an individual rider may move more slowly.