chapter 18 chapter 19

Diffraction and Interference of Light

Francesco Maria Grimaldi noticed that the edges of shadows were not perfectly sharp, so he named the slight spreading of light waves, diffraction, which is the bending of waves around the edges of barriers. According to Christian Huygens, you can replace the crest of any wave by equally spaced wave that produce new waves with one another. In his experiment, light fell on two closely- spaced narrow slits. The light that passed through each slit was diffracted. As a result, the spreading light from the two slits overlapped when the light fell on an observing screen, the overlap produced a pattern of bright and dark bands called interference fridges.

  • When colored spectra is seen when white light is used in a double-slit experiment

  • The position of the bands depend on the wavelength, so that the light is seperated by diffraction into a spectrum of color at each band

  • Light that passes through a single slit, produces many bright and dark bands that are spaced around a bright central band

  • When the width of the opening is the same as the wavelength of light, diffraction is at its maximum

  • When looking for the distance of the central band to the dark band, use the equation
    x=wavelength multiplied by the L divided by the W
  • ^=Light Wavelength

  • L=distance to screen

  • w=slit width

  • To solve the wavelength:^=(x)(d)/L

    • Diffraction Gratings

    Do you know that beetles and butterflies produce their colors through diffraction. The tiny ridges that cover the butterfly's wings each diffract the light each diffract the light hitting them, producing interference effects. The slits that make The slits that make the interference pattern of two slits stronger is called a diffraction grating. these are made by scratching very fine lines with a diamond point on glass. Diffraction gratings are used to create interference pattern sto analyze light sources. As a result, colors are easily distinguished, which means that wavelengths can be measured more precisely than with double slits. The same equation can be used for a diffraction grating where d is distance between lines
    X divided by L=wavelength divided by d
  • This equation is used for diffraction grating

    • (x)(d)=(wavelength)(L)
  • the lens diffracts the light, so the smaller the lens, the wider the diffraction pattern

  • Diffraction limits the resolving power of lenses. The effects of diffraction on the reolving power of the telescope can be reduced by increasing the size of the lens. Even though the wavelength of light can be reduced, the objective lens of a microscope cannot be enlarged

    • References

  • electron9

  • Holography for the New Millinium

  • Why Things Are The Way They Are

  • Merrill-Physics Textbook-Principles and problems