How to Make a Spectroscope at Home with household item.

A spectroscope is a device that lets us find out what things are made of. It works by taking light and splitting it up into its component colors. Different elements make different colors when they glow. We can make objects and gasses glow by heating them up in a flame, or by passing electricity through them. The spectroscope spreads out the colors of the light, and we can identify the elements by the bright lines we see in the spectroscope.

Fluorescent light

The photograph above was made using the homemade spectroscope we will make in this project. You can see a bright green line, a bright blue-purple line, and a fainter orange line. These lines tell us that the element mercury is making some of the light. The light is coming from a fluorescent light bulb, and these bulbs work by heating up mercury until it glows. The blue-purple light from the mercury (and some invisible ultraviolet light just beyond the blue-purple line) then makes the white phosphor coating on the inside of the glass tube fluoresce bright white.

How to make a spectoscope Click on photo for larger picture

What we will need: A CD or DVD that can be sacrificed to this project. We won't damage it, but getting it back will involve destroying our spectroscope. Old software CDROMs work great, and some can be had for free from internet service providers like AOL. A cardboard box. An 8 inch cube works fine, but any size that can hold a CD or DVD disk will do. Two single edged razor blades. These can be found in paint or hardware stores. A small cardboard tube, the kind used as a core to wrap paper on. Some cellophane tape. Some aluminum tape (found in hardware stores), or some aluminum foil and glue.

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Our spectroscope has three main parts. There is a slit made from two razor blades, a diffraction grating made from a CD disk, and a viewing port, made from a paper tube.

To make sure that all three parts are lined up properly, we will use the CD disk as a measuring device, and mark the spots where the slit and the viewing port will go.

Set the CD disk on top of the box, about a half inch from the left edge, and close to the box's bottom, as shown in the photo. Use a pen to trace the circle inside the CD disk onto the box. This mark shows us where the paper tube will go.

Click on photo for larger picture Also See: How to make a Aeroplane that Can Fly   Rocket Engien at home

Now place the paper tube on the box, centered over the circle we just drew. Draw another circle on the box by tracing the outline of the paper tube.

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Move the paper tube over a little bit. A half-inch is probably fine -- in the photo I placed it much farther to the right than necessary, but the aluminum tape covered up the mistake nicely. Trace another circle around the paper tube. These circles will tell us where to cut the box.

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Now cut an oval out of the box with a sharp knife. The oval will allow the paper tube to enter the box at an angle.

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The next step is to make the slit. Turn the box one quarter turn so the oval we just cut is to the right. Using the CD disk again, draw another small circle close to the left side of the box.

The slit will be on the far left of the box. Cut a small rectangle out of the box at the height marked by the small circle we made with the CD disk. The rectangle should be about a half inch wide, and two inches high.

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Carefully unwrap the two razor blades, and set them over the rectangular hole. Make their sharp edges almost touch. Tape the razor blades to the box, being careful to leave a gap between the sharp edges that is nice and even, and not wider at the top or bottom.

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Next, set the box right-side-up, with the slit towards you. Now tape the CD disk onto the back wall of the box. The rainbow side should face you, with the printed side touching the cardboard. The photo shows the disk a little too far to the left. The left edge of the disk should be the same distance from the left of the box as the slit is.

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Now seal up any places on the box where light might leak in. Use the aluminum tape for this. You can also use aluminum foil for this purpose if you don't have any aluminum tape.

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The last step is to use the aluminum tape to attach the paper tube. The aluminum tape will make a light-tight seal around the tube. To make sure the angle is correct, hold the slit up to a light, and look through the paper tube, adjusting it until you can see the full spectrum from red to purple.

That's it! We are ready to use the spectroscope.

How to use the spectoscope

Hold the slit up to a source of light. An incandescent light will show a simple spectrum with no bright lines. This is because the light comes from a hot solid (the tungsten filament in the light bulb).

Hot gasses will produce light that is made up of only a few colors. The spectroscope will spread these colors out, so we can see them individually.

Neon light bulb

The photo above shows the light from a neon light bulb. We can see that the hot neon gas is made of several colors, but they are mostly in the red and orange parts of the spectrum.

Light is made up of waves, and each different wavelength is a different color. The neon light is showing waves of these lengths: 540 nanometers (very faint) green 585 nanometers yellow 588 nanometers yellow 603 nanometers orange 607 nanometers orange 616 nanometers orange 621 nanometers red-orange 626 nanometers red-orange 633 nanometers red 638 nanometers red 640 nanometers red 650 nanometers red 660 nanometers red 692 nanometers red 703 nanometers red

Red light-emitting-diode (LED)

A red LED makes light, but there is no hot gas, so it has a continuous spectrum.

Green light-emitting-diode (LED)

Some green LEDs look very green. Others look more like a yellowish-green. By looking at their spectrum, as in the photo above, we can see that the yellow-green LEDs have a lot of green, but also some yellow, orange, and red.

Laser diode

The LEDs we looked at had broad spectra. Their light consists of many different wavelengths. A red laser diode has a much narrower spectrum. It has only a few different wavelengths, and is said to be monochromatic , meaning "one color".

White light-emitting-diode (LED)

A white LED is actually a blue LED and a phosphor. It works in a way similar to the fluorescent light bulb, where the blue light excites the phosphors to make a white glow.

We can see the broad spectrum in the spectroscope. The dark band in the photo is the bare spot on the CD disk close to the center. The spectrum is so broad that it covered the entire width of the CD.

The photos above were done using a spectroscope made from an audio CD. The photo below was done using a DVD, which has lines that are closer together. The closer lines cause the spectrum to spread out a little more.

Mercury vapor spectrum in fluorescent light

The spectrum is not quite spread enough to show the two orange lines as separate lines. A diffraction grating with finer lines would show finer distinctions, allowing us to distinguish elements better. Tag:Making a spectroscope ,make a spectroscope at home,make a spectroscope with house hold items, spectroscope at home,spectroscope making at home. Also See: Make a Permanent Rainbow Make a Battery at home with house hold items.

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