Tuesday, April 12, 2011

Waves: Refraction, Diffraction, and Interference

Refraction of light through glass. Photo by Joost J. Bakker.
Refraction is the bending of a wave as it its speed changes (usually as a result of going from one medium to another). Light provides an excellent example of refraction as it passes from glass to air or from water to air. However, other types of waves can refract as well. Consider a sound wave... ... Can sound refract? Do a little poking around on the internet. Can you find any descriptions of physical phenomena that can be explained by sound refraction?

Diffraction is the bending of light as it passes near an edge. In class we saw how a human hair can diffract a beam of laser light to form an interesting pattern. Look up the term "diffraction grating." What is it and what it is used for?

Interference occurs when two or more waves occupy the same space at the same time. There are many animations and simulations available online to help to visualize wave interference. My favorite is the virtual wave table on the phet site. Search around and post a link to a site you find useful.
Posted by Brian Bearss at 2:17 PM

8 comments:

  1. EsmereldaApril 13, 2011 at 7:44 AM

    Diffraction grating is an optical device used to learn the different wavelenghts and colors contained in a beam of light. A diffraction grating can be used as the main dispersing element in a spectograph.

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  2. Cheno SenApril 13, 2011 at 7:47 AM

    http://micro.magnet.fsu.edu/primer/java/scienceopticsu/interference/waveinteractions/index.html

    When searching i found this website helpeful for interference. It lets you change the wavelength phase and amplitude of two waves and show you above the differences.

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  3. CharlotteApril 13, 2011 at 7:57 AM

    Diffraction Grating is optical device used to learn the different wavelengths or colors contained in a beam of light, gratings are commonly used in monochromators and spectrometers.

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  4. alphadogApril 13, 2011 at 10:04 AM

    It does some research on refraction of sound waves and found it quite interesting in that it explained the reasoning behind why you can hear a family across a body of water better at night opposed to in the day. It explained the mediums to which the sound passes through as cold and warm temperatures. In the day time the air closest the ground is warmer than the air farther away, thus, sound can travel faster through the more molecularly active warmer air faster than that of the air above it. This produces an upwards bending effect. In the night time however the temperature placements change places to where it is warmer farther from the ground. This causes a downward bending of the sound wave allowing the person to hear the sound at a greater distance. The website below explains it better than me I think if you'd like to check it out.

    http://paws.kettering.edu/~drussell/Demos/refract/refract.html

    Also for others posting I think you would find very interesting information with the refraction of light when it comes to the earth's atmosphere.

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  5. Brian BearssApril 13, 2011 at 10:25 PM

    Good points, alphadog!

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  6. SNICKERSApril 14, 2011 at 11:22 AM

    Yes sound can refract, and found a nice website to explain it.

    http://paws.kettering.edu/~drussell/Demos/refract/refract.html

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  7. sciencegeek101April 18, 2011 at 9:15 AM

    Diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions. Because of this, gratins are commonly used in monochromators and spectrometers.

    Monochromators is an optical device that transmits a mechanically selectable small band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. Spectrometers is an instroment used to measure propteries of light over a certain portion of the electromagnetic spectrum.

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  8. Brian BearssApril 18, 2011 at 2:10 PM

    Thanks for the comments this week!

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