These highly efficient, double axis, holographic diffraction grating lenses separate light from any source into its spectral components for study and analysis. Lenses are mounted in sturdy cardboard frames. Sold in sets of 10.
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When we begin learning about light, we usually start by talking about the colors of the spectrum and the fact that white light can be broken up, or dispersed into a spectrum of colors. To disperse light into its spectrum, Sir Isaac Newton used a prism. However, in recent years the diffraction grating has replaced the prism for this purpose because it is easier, more effective, and less expensive.
Diffraction gratings are not new. They've been the basis of spectroscopic instruments for a long time, but these instruments are not necessary for many learning purposes. You can see the exciting and detailed spectra simply by holding a diffraction grating up to your eye and looking through it at a light source in a dark place.
Eventually, the question arises, 'How does a diffraction grating work?' It's not easy to find an answer to this question that doesn't get mathematical, yet explains the principal in a satisfying way. The following attempts to do that.
Waves in a Pond
Light waves are similar to water waves in many respects. Let's start with the familiar situation of water wave ripples due to a dropped pebble. Their spread (concentric circles) can be understood by considering each point along a wave, or wave front, to be the source of a new wavelet, each source having the same phase.
Now let's apply this to a wave that encounters an obstruction such as a narrow slit. The wave spreads out in a circular pattern. The difference between successive peaks or valleys is called the wavelength.
Now let's increase the number of narrow slits, equally spaced. This is called a diffraction grating.
When a light wave encounters a diffraction grating, the light spreads as if it originated from many point sources, each in phase with one another. Each wave spreads out in a circle, but now there are centers at each slit. If one wavelet's peak lies on another wavelet's valley, the result is neither peak nor valley, but rather cancellation. However, if one wavelet's peak lies on another wavelet's peak, they add constructively, making a wave twice as high.
There are special directions where cancellation is avoided and the wavelengths add constructively. The direction is different for different colors because different colors have different wavelengths. For example, since the wavelength of red light is longer than the wavelength of blue light, a red beam is diffracted or bent further than a blue beam when it passes through the diffraction grating.
This is how a diffraction grating breaks up the colors of white light. White light has many colors. Between red and blue are other colors, like orange, yellow, and green, whose wavelengths are intermediate between those of red and blue light.
Putting all this together, we can see how a beam of white light, which contains all the colors, gets diffracted or bent into a spectrum of colors.
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Great inexpensive demonstration
Jan 8, 2018 | By JHemel of Portland, OR United States
These are great
Jun 11, 2015 | By Echo Johnson of Hastings, MI United States
Feb 4, 2013 | By Neal Leatherman of Batavia, IL United States
Not as good as picture
Aug 28, 2012 | By Allan of Las Vegas, NV United States
May 29, 2012 | By Matthew of chattanooga, TN United States
May 25, 2012 | By Cheri Dennen of North Port , FL United States
8th Grade Science Teacher
May 22, 2012 | By Linda Guillory of Kennesaw, GA United States
This product will support your students' understanding of the Next Generation Science Standards (NGSS)*, as shown in the table below.
Suggested Science Idea(s)
Students can conduct investigations showing evidence of illumination from an external source such as the Sun.
Students can use this tool to conduct an investigation of how different materials affect the path of a beam of light.
Students can use this tool to develop and use a model to describe how waves are reflected, absorbed, or transmitted through various materials.
Students can use lenses to conduct investigations and use mathematical representations to support a claim regarding relationships among the frequency, wavelength, and speed of waves traveling in various media.
Students can use the Prism Glasses to conduct investigations about technological devices use the principles of wave behavior and wave interactions with matter to transmit.
Students can use this tool to develop and use a model to how waves are reflected, absorbed, or transmitted through various materials. These glasses are excellent for viewing visible light in rainbow form. Caution! Never look directly into the sun with these glasses.
* NGSS is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, this product.