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Electromagnetic Spectrum (EMR)

Electromagnetic Spectrum (EMR). Transverse waves Which waves are considered extremely dangerous? What is the relationship btwn λ and f ? E and f ? Equipment: Prism Spectroscope uses a diffraction grating to separate the colors. Dispersion. R O Y G B I V. IAN . Optics. Light Waves

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Electromagnetic Spectrum (EMR)

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  1. Electromagnetic Spectrum (EMR) • Transverse waves • Which waves are considered extremely dangerous? • What is the relationship btwnλ and f? E and f? • Equipment: • Prism • Spectroscope uses a diffraction grating to separate the colors Dispersion ROYGBIV

  2. IAN Optics Light Waves 7C, 7D, 7E, 7F

  3. Dispersion ROYGBIV

  4. Mirrors(angle of incidence Θi= angle of reflection Θr) Normal line 1 2 3 • Laterally inverted (180°) • Real image- formed as a result of interception of light • Virtual image- not actually there b/c light doesn’t meet 4 5 6 7 8

  5. r is less than i r is greater than i Refractionthe change in direction of waves as they pass from one medium to another as a result of a change in speed More love, more hugs Less love, less hugs

  6. Total Internal Reflection i= angle of incidence r= angle of reflection If i= Critical angle (c) Angle of refraction= 90° If iis increased air air air N N N r r r i i i water water water Conditions for total internal reflection : ray travels from optically more dense to less dense i c air N i r water If i c Totally internally reflected

  7. F F Convex Lenses (converge- rays comes together) Real image Concave Lenses (diverge- rays go away from each other) Virtual image Convex lenses are positive converging lenses. Concave lenses are negative diverging lenses.

  8. A n1 = 1.0 n2 = 1.5 B Refractionthe change in direction of waves as they pass from one medium to another as a result of a change in speed • More love, more hugs (l→g= towards normal line) • Less love, less hugs (g→l= away from normal line) • Physical property that tells how much a material “bends” light • When going from less dense to more dense, ray bends toward the normal • When going from more dense to less dense, ray bends away from the normal • Can differ from the material’s normal density • n= refractive index (light bending ability of a material) air Optical Density N i= angle of incidence r= angle of refraction i plastic r Material Refractive Index (n) Verizon FIOS (Total Internal Reflection)

  9. Why does the rearview mirror state objects may be closer than they appear? Lens Convex (magnifier) Concave (de-magnifier) Concave- diverging lens Creates virtual images • Convex- converging lens • Creates real images Plano Convex Plano Concave Double Convex Double Concave Convex Meniscus Concave Meniscus Farsighted people use lenses similar to these. Nearsighted people use lenses similar to these.

  10. Image Formation by Convex Lenses Principal Focus (F) Optical Center Object Principal axis 2F F F’ 2F’ image Lens focal length (f) Principal axis- line through optical center of the lens Optical Center- point where principal axis and center of lens intersect Principal focus (F)- focal point at which the light ray passes through the principal axis Focal length (f)- distance from the optical center and the principal focus 2F- double the focal length

  11. If object is between F and Lens • Erect virtual image • same side as object • Image bigger • Beyond 2F’ • Ex. microscope& hand lens Principal axis 2F F F’ 2F’ No image formed b/c light ray doesn’t intersect If object is at 2F F’ 2F’ Principal axis 2F F • Inverted real image • Opposite side of object • Image same size • Formed at 2F’ • Ex. copy machine

  12. If object is between 2F & F • inverted real image • opposite side of object • Image bigger • Beyond 2F’ • Ex. projector Principal axis 2F F F’ 2F’ If object is at Beyond 2F F’ 2F’ Principal axis 2F F • Inverted real image • Opposite side of object • Image smaller • Formed at between F & 2F • Ex. camera

  13. Light Rays and Convex Lenses • erect virtual image • same side as object

  14. How You See • Near Sighted (Myopia)– Eyeball is too long and image focuses in front of the retina • Concave lenses expand focal length • Far Sighted (Hyperopia)– Eyeball is too short so image is focused behind the retina. • Convex lenses shortens the focal length. What happens to light entering the eye when the condition of nearsightedness exists?

  15. Total Internal Reflection i= angle of incidence r= angle of reflection If i= Critical angle (c) Angle of refraction= 90° If iis increased air air air N N N r r r i i i water water water Conditions for total internal reflection : ray travels from optically more dense to less dense i c air N i r water If i c Totally internally reflected Verizon FIOS

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