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Single Axis Diffraction Grating NGSS

  • Single Axis Diffraction Grating (6 in. x 24 in. sheet)
    Item #: PG-400
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  • Single Axis Diffraction Grating (30 pack of slides)
    Item #: PG-415
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Gives brilliant spectra with fluorescent lights, flame tests, gas discharge tubes or even holiday lights!

Description

This has been one of our most requested products. Although we love our double axis diffraction gratings (see item PG-2), sometimes it is easier to use a single axis diffraction grating for measuring emission spectra in the classroom laboratory. Educational Innovations is happy to offer this superior grade single axis grating. It gives brilliant spectra with fluorescent lights, flame tests, gas discharge tubes, or even holiday lights! Try both. 500 lines/mm, 6" x 24" piece (approx 15.25 x 61 cm). Also available in slides (35 mm x 24 mm diffraction material mounted in 2" x 2" slide frame - 30 per package).

Lesson Ideas

Download the pdf of this lesson!

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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Reviews

5 reviews
Mr.
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Gratings are of high quality, reasonable price. Delivery was prompt.
Evan Jones

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Defraction gratings
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very satisfied
john t huston

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Single axis diffraction grating
Review star icon Review star icon Review star icon Review star icon Review star icon May 24, 2012
These gratings replace some multiple axis gratings which we previously had. The grating spacing also comes close to the few glass diffraction gratings we have. These gratings are good enough to clearly seee the pattern and are inexpensive enough to pass around and handle.
Laurence Rowe

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High Quality & Easy to Use!
Review star icon Review star icon Review star icon Review star icon Review star icon May 22, 2012
We have been using the diffraction grating for over 8 years in after school programs in local elementary schools. It is the perfect low-cost addition to a toilet paper roll, tape, and construction paper to make low cost spectroscopes. Over 80 students each year use the product and take it home! Love it!
Bernadette Garcia

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Excellent Product!
Review star icon Review star icon Review star icon Review star icon Review star icon May 16, 2012
An excellent product. I have used this to take images of the spectra of light sources such as gas discharge tubes, night-time street lamps, and stars. Just cut a piece to size, tape to your digitial camera lens body, or DSLR, and viola you have a cheap digital spectroscope!
Jennifer Birriel

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NGSS

This product will support your students' understanding of the Next Generation Science Standards (NGSS)*, as shown in the table below.

Elementary Middle School High School

1-PS4-2

Students can conduct investigations showing evidence of illumination from an external source such as the Sun.

1-PS4-3

Students can use the Diffraction Grating to conduct an investigation of how different materials affect the path of a beam of light.

MS-PS4-2

Students can use the Diffraction Grating to develop and use a model to describe how waves are reflected, absorbed, or transmitted through various materials.

HS-PS4-1

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.

HS-PS4-5

Students can use the Diffraction Grating to conduct investigations about technological devices use the principles of wave behavior and wave interactions with matter to transmit.

Suggested Science Idea(s)

1-PS4-2
1-PS4-3
MS-PS4-2
HS-PS4-1
HS-PS4-5

Students can use the Diffraction Grating to develop and use a model to how waves are reflected, absorbed, or transmitted through various materials. Diffraction Grating is excellent for viewing visible light in rainbow form. Caution! Never look directly into the sun with this.

 

* 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.

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