What is the nature of light?

1. What is the nature of light? • Light waves are different from other kinds of waves. • Light waves are vibrating electric and magnetic fields that transfer energy through space.

2. An electromagnetic wave is a disturbance that transfers energy through a field. FYI: Electromagnetic Waves A field is an area around an object where the object can apply a force to another object without touching it. An electromagnetic wave can travel through a vacuum (empty space). The disturbance of an electromagnetic wave can occur within and electric or magnetic field.

3. Because the light travels faster than the sound. wavelength amplitude

4. What determines the color of light? • Like all waves, light has wavelengths • Different wavelengths of light are perceived by our eyes as different colors • White light is what we perceive when we see all the wavelengths of light at once, in equal proportions • Our eyes only register three colors of light: red, green, and blue.

5. Wavelengths determine color. Visible Light = on the EM Spectrum visible light has many different wavelengths. When all of the wavelengths are together, light from the sun or a light bulb, the light appears white. Left = longest wavelengths with lowest frequencies and energies. Right = shortest wavelengths with high frequencies and energies.

6. Violet, blue, green, yellow, orange, red

7. Light and Color (6:39)

8. What are the parts of the EM spectrum? • EM waves are measured by frequency or by wavelength • The range of frequencies that EM waves can have is called the electromagnetic (EM) spectrum.

10. EM Spectrum

11. How can matter interact with light? • Matter can transmit light • Matter that transmits light is transparent. (objects can be seen clearly) • Matter that transmits light but scatters it in all directions is translucent. (objects look distorted or fuzzy)

12. How can matter interact with light? • 2. Matter can absorb light • Absorption is the transfer of light energy to matter. • Opaque materials do not let any light pass through them because they reflect light, absorb light, or both. The table is opaque, because light does not pass through it. We can’t see through it.

13. Transparent, Translucent, Opaque

14. How can matter interact with light? • 3. Matter can reflect light • Reflection is the bouncing of light off a surface. • When light strikes a smooth surface, the light bounces off at an angle equal to the angle at which it hit the surface http://www.classzone.com/books/ml_science_share/vis_sim/wslm04_pg115_reflection/wslm04_pg115_reflection.html

15. The shirt absorbs light, while the mirror reflects light.

16. What determines the color of objects we see? Color is determined by the wavelength the object absorbs or reflects If an object reflects all wavelengths of light it will appear white. If an object absorbs all wavelengths of light it will appear black. If an object absorbs most wavelengths of light but reflects one color, the object will appear that color (like a yellow banana).

17. What determines the color of objects we see? Transparent and translucent objects work differently. Objects may absorb some colors but let other colors pass through them (transmit the light wave).

18. Reflected Light

19. What happens when light waves interact with matter? • Light slows when it passes through matter. The speed of light in a vacuum is about 300,000,000 m/s. • Light bends when it passes at an angle from one medium to another. • The bending of a wave as it passes from one medium to another is called refraction. • Refraction occurs because light changes speed as it enters a medium at an angle. red

20. Refraction of Light Slows down Speeds up

21. Refraction and Rainbows

22. The Nature of Light (4:25)