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Warm Up 6.2

Warm Up 6.2. List the colors of the visible light spectrum Which color has the longest wavelength Which color has the most energy? (hint: shorter wavelengths have the most energy). Light. How light waves interact with materials. Light can be reflected, transmitted, or absorbed.

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Warm Up 6.2

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  1. Warm Up 6.2 • List the colors of the visible light spectrum • Which color has the longest wavelength • Which color has the most energy? (hint: shorter wavelengths have the most energy)

  2. Light

  3. How light waves interact with materials • Light can be reflected, transmitted, or absorbed. • Materials can be classified according to the amount and type of light they transmit

  4. Transparent- Transparent Materials allow most of the light that strikes them to pass through Examples: windows, light bulbs, clock faces, ziploc bags

  5. Translucent- Translucent Materials transmit some light, but they also cause it to spread out in all directions Examples: lampshades, sheer fabrics, frosted glass

  6. Opaque- Opaque Materials do not allow any light to pass through them because they reflect light, absorb light, or both. Examples: heavy fabrics, wood, rocks, construction paper

  7. Visible Light • Part of the EM spectrum we can see • Red, Orange, Yellow, Green, Blue, Indigo, & Violet (ROY G BIV) • Red has the longest wavelength • Violet has the most energy

  8. What determines color of an object? • 2 factors determine the color of an object • The wavelengths that the object itself reflects or absorbs • The wavelengths present in the light that shines on the object

  9. Color Reflection & Absorption • Reflection • Absorption • White Color • Black Color • Wavelengths that an object bounces back and are seen • Wavelengths that are absorbed and not seen • Is seen when all the wavelengths are reflected • Is seen when all the wavelengths are absorbed

  10. Wavelengths Present • Ex: If you only shine red light on a white piece of paper, the paper will appear red, not white- • Red light is the only light that is available to be reflected

  11. Primary Colors of Light vs. Primary Pigments Primary Colors of light Primary Pigments Cyan, yellow, & magenta are the primary pigments When all 3 are mixed together, they make black • The human eye can only detect- red, green & blue. • When all 3 are mixed together equally they make white light

  12. same angle surface normal Reflection • We describe the path of light as straight-line rays • Reflection off a flat surface follows a simple rule: • angle in (incidence) equals angle out (reflection) • angles measured from surface “normal” (perpendicular) exit ray reflected ray incident ray

  13. Reflection Vocabulary • Real Image – • Image is made from “real” light rays that converge at a real focal point so the image is REAL • Can be projected onto a screen because light actually passes through the point where the image appears • Always inverted

  14. Reflection Vocabulary • Virtual Image– • “Not Real” because it cannot be projected • Image only seems to be there!

  15. “real” you “image” you PLANE MIRRORFlat Mirror ex: Hall Mirror • Useful to think in terms of images mirror only needs to be half as high as you are tall. Your image will be twice as far from you as the mirror.

  16. PLANE MIRRORLEFT- RIGHT REVERSAL AMBULANCE

  17. Curved mirrors • What if the mirror isn’t flat? • light still follows the same rules, with local surface normal • Parabolic mirrors have exact focus • used in telescopes, backyard satellite dishes, etc. • also forms virtual image

  18. View kacleaveland's map Taken in a place with no name (See more photos or videos here) "Have you ever approached a giant concave mirror? See your upside-down image suspended in mid-air. Walk through the image to see a new reflection, right-side-up and greatly magnified. In the background you see reflected a room full of visitors enjoying other Concave Mirrors • Curves inward • May be real or virtual image

  19. Convex Mirrors • Curves outward • Reduces images • Virtual images • Use: Rear view mirrors, store security… CAUTION! Objects are closer than they appear!

  20. Refraction • Rate at which material slows down speed of light • The “light slowing factor” is called the index of refraction • glass has n = 1.52, meaning that light travels about 1.5 times slower in glass than in vacuum • water has n = 1.33 • air has n = 1.00028 • vacuum is n = 1.00000 (speed of light at full capacity)

  21. Convex Lenses Thicker in the center than edges. • Lens that converges (brings together) light rays. • Forms real images and virtual images depending on position of the object The Magnifier

  22. Concave Lenses • Lenses that are thicker at the edges and thinner in the center. • Diverges light rays • All images areerect and reduced. The De-Magnifier

  23. How You See • Near Sighted – Eyeball is too long and image focuses in front of the retina • Near Sightedness – Concave lenses expand focal length • Far Sighted – Eyeball is too short so image is focused behind the retina. • Far Sightedness – Convex lens shortens the focal length.

  24. Mirror Mini-Lab • Hold the convex mirror arm length away and record your observations as you move it slowly towards your face. • Ex: Are you Big or Small? Fuzzy or clear? Right side up or Upside Down? • Does any thing change as you move it closer? • Repeat using the concave mirror.

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