1 / 105

# Light

Light. The EKG showed that Sound is another form of electricity Your body has currents moving through it We emit strong magnetic fields The device charges up your body periodically. The speaker/microphone helped us to see that: Electrical currents can be produced from a moving magnet

## Light

E N D

### Presentation Transcript

1. Light

2. The EKG showed that • Sound is another form of electricity • Your body has currents moving through it • We emit strong magnetic fields • The device charges up your body periodically

3. The speaker/microphone helped us to see that: • Electrical currents can be produced from a moving magnet • Sound is really a form of electricity • There is no magnetism involved in the conversion from sound to electrical current • Sound waves can only be emitted from electrical activity, not the other way around

4. Light travels VERY FAST – around 300,000 kilometres (186282 miles) per second. At this speed it can go around the world 8 times in one second.

5. HIGH energy LOW energy

6. The Full Electromagnetic Spectrum • Visible, Infrared and UV radiation are only part of the full spectrum of electromagnetic radiation Source: http://www.mhhe.com/physsci/astronomy/arny/instructor/graphics/ch03/0305.html

7. The Sun’s Radiation Spectrum • ~ 43% is in the visible range • ~ 49% is in the near infrared range • ~ 7% is in the ultraviolet range • < 1% is x-rays, gamma waves, and radio waves Most of the sun’s radiation is UV, Vis & IR : . Source: Adapted from http://www.ucar.edu/learn/imgcat.htm

8. Sunset

9. By passing white light through a prism, • you can tell- • A that white light is actually a mixture of different colors • B the mass of the prism • C the original source of the light • D that blue light is brighter than white • light

10. Pick up nov 4

11. Did you vote? • Yes! • No… • I am not able to vote

12. Do you think that your vote “counts?” • Yes, definitely • Only indirectly • Only if it is a close call • No

13. November exam Exam this month – push back a week? • 10-Nov is ok • Prefer 17-Nov • No exam at all is preferable Final: Wed Dec 15, 4:30-7pm (I think this room)

14. Do you want to go over the “nuclear” exam in Thursday discussion session? • Yes • No • Indifferent

15. What about for the circuits hw? • Yes • No • Indifferent

16. Bees see in UV

17. Additive Colors • Red, Green, and Blue light sources can be used to synthesize almost any perceivable color • Red+ Green = Yellow • Red + Blue = Magenta • Green + Blue = Cyan • These three dual-source colors become the primary colors for subtraction • why? because absence of green is magenta • absence of red is cyan, etc.

18. Pick up Nov 9

19. Term project – to be worth more? Do you find it fair to change the grading scheme for this course based on a class vote? • Yes, if >50% is ok with it. • Yes, but only if >67% is ok with it. • Not really, but I’ll go along with it. • No way!

20. Term project – to be worth more? There are multiple ways to slice it – • Midterms=13%,final=20%, term=18% • Midterms=13%,term=15% • Midterms same, final 20%, term 14% • Keep the current scheme

21. Democracy! Are you ok with what “we” just decided? • Yes • No

22. Invisibility cloak?

23. One-way mirrors How do they work? • Special engineered one-way material • Bright reflected rays on one side • Interference of light rays • Refraction of light rays

24. Part 2 - Reflection Reflection from a mirror: Normal Reflected ray Incident ray Angle of reflection Angle of incidence Mirror

25. A “light-pipe” works by • Diffraction • Interference • Refraction • Dispersion

26. Homework Seeing colour • The colour an object appears depends on the colours of light it reflects. For example, a red book only reflects red light: White light Only red light is reflected

27. pick up Nov 11

More Related