1. CHAPTER 14 LIGHT AND COLOR

2. We need to mash together what we know about electricity magnetism
When electric fields and magnetic fields vibrates
Electromagnetic Waves .
Electric fields change by changing magnets
Magnetic fields change by changing electric currents
All electromagnetic waves in a vacuum TRAVEL AT THE SAME SPEED ….
300,000 KM/S , 000 MI/S

4. Why can you see through some materials (TRANSPARENT ) while other materials you can’t see through( OPAQUE)?
When light hits a material , electrons within materials atoms are stimulated to VIBRATE If the VIBRATIONS are LARGE and LONG LASTING the energy is absorbed and the material appears opaque to that frequency. LIGHT CAN BE ABSORB OR REFLECTED DEPENDING ON SURFACE TYPE

5. If the VIBRATIONS are SMALL and SHORT LIVED the energy is remitted and the material appears transparent
There is a time delay between absorption and reemission – DIFFERENT MATERIALS ALLOW LIGHT THROUGH AT DIFFERENT SPEEDS
glass 2/3 the speed of light
water is ¾ the speed of light
Glass can be made to be transparent to a variety of ELECTROMAGNETIC MATERIALS

7. Glass is …. transparent to VISIBLE LIGHT opaque to INFARED LIGHT opaque to ULTRAVIOLET LIGHT

8. Color Science
Visible light color differs according to frequency

9. Highest Frequency Light we can detect is VIOLET and the Lowest Frequency Light we can detect is READ The pneumonic device to remember the order of colors ROY GEE BIV Red Orange Yellow Green Blue Indigo Violet

10. White is the mixture of all light together
Black is the absence of light
Colors we see are the frequency of light the object REFLECTS BACK TO US
Transparent objects appear the color they transmit
Fluorescent Lamps have more BLUE AND VIOLET
Incandescent Lamps have more RED AND ORANGE
Sun Light more GREEN and RED

11. WHITE OBJECTS REFLECT BACK ALL COLORS OF LIGHT AND TEND TO BE COOLER IN TEMPERATURE
THE DARKER COLOR AN OBJECT THE MORE ENERGY IT TENDS TO ABSORB AND THE WARMER IT TENDS TO BE

12. MIXING OF COLORS
THE SUN TENDS TO BE MOST INTENSE IN THE YELLOW –GREEN WAVELENGTH
THAT IS WHAT PLANTS TEND TO ABSORB MOST AND OUR EYES SEE BEST
RED GREEN BLUE ARE THE PRIMARY COLORS – TOGETHER THEY MAKE WHITE

13. SECONDARY COLORS – TWO PRIMARY COLORS
RED + GREEN = YELLOW
RED + BLUE = MAGENTA
GREEN + BLUE = CYAN
COMPLEMENTARY COLORS – ANY TWO COLORS THAT MAKE WHITE
MAGENTA + GREEN
YELLOW + BLUE
CYAN + RED

14. Why is the Sky Blue ? Light from the sun is absorbed by the Nitrogen
(78% ) and Oxygen (21%) atoms in the atmosphere and reemitted( scattered ) in all directions
The highest frequency light( violet and blue ) are
scattered the most , our eyes are not as sensitive to violet as they are to blue.

15. As the frequency of light decrease the amount it is reemitted also decreases- SO red is scattered the least. Water vapor/ Dust/ Smoke absorb other frequencies of light and reemit them causing a whitening in the sky. Larger particles or water droplets do not reemit light as much causing a darkening. Water has a faint cyan color and absorb red light

16. Why are sunsets Red?
Light that is not absorbed by atmosphere goes right through( transmitted ) ROY are not scattered
Noon sunlight travels through least amount of atmosphere – appears pale yellow
Sunset and Sunrise travels through most atmosphere VB scattered out – RO make it through to us. Pollution makes sunset more colorful

17. Why are clouds white ?
Water droplets that make clouds come in many sizes – the very smallest drops absorb and reemit violet light.
As droplets get bigger the larger the wavelength of light they absorb and reemit.
All colors scattered – makes white,