Category Archives: Science fair ideas

Homemade Photocell

Today, we have another science fair project suitable for students who like to use dangerous chemicals. It’s a homemade photoelectric cell. It won’t provide large amounts of current, but it is measurable, and it can probably be used to receive a signal from a modulated beam of light, simply by connecting it to an audio amplifier (similar to this previous project).

The cell consists of a beaker of water in which a “pinch” of salt has been added. Into this are inserted strips made of copper and lead. The copper is heated with a torch to oxidize it, after which it is scrubbed with nitric acid. There is some current even in darkness, but when the copper strip is exposed to light, the current increases.

The project appeared in the November 1948 issue of Practical Wireless.

Science Fair AC Generator

If Junior is looking for a simple science fair project, albeit one that probably can’t be whipped together at 10:00 PM the night before it’s due, he or she can’t go wrong with this simple AC generator from the November 1963 issue of Electronics Illustrated.

The design is very straightforward. To avoid having to worry about brushes, the coil stays stationary, and the permanent magnet turns. The coil consists of 800 turns of number 28 or 30 enameled wire on a 2 or 3 inch iron bolt.

The magazine recommends using a DC ammeter, with the calibration set so that 0 is mid-scale. As the crank is turned slowly, the needle will deflect first one direction, and then the other.

Another possibility would be two LED’s in parallel, each pointing a different direction. As Junior slowly cranks the handle, the lights will alternate, and as the speed picks up, they will both appear lit.

For more projects, some of which can be whipped together at the last minute, browse our other science fair ideas.

1963 Student Experimental Licenses

Shown here, in the September 1963 issue of Popular Electronics, is Albert Pabin (I believe with the headphones) and two other students demonstrating an audio console by using it during an actual broadcast. Pabin was a ninth-grade student at Utica Free Academy, Utica, NY. His science project was the console he designed and built, and he wanted to demonstrate it under actual broadcast conditions.

To do so legally, he procured an experimental license from the FCC, and was able to go on the air, on 27 MHz, with the call KF2XGJ. According to the magazine, the FCC rules made provision for student experimental licenses for students, seventh grade and above, who had “a good idea of what he is trying to show, and that he have older and more knowledgeable persons available to help him in case of difficulty.” In particular, “the FCC believes that a student’s instructors are fair judges of his motives and sincerity, and looks favorably on projects endorsed by an instructor.” Notice to the FCC Engineer-In-Charge for the district was also required.

The application required various technical descriptions of the transmitter, as well as a statement from the principal or faculty member, on school letterhead, stating that the project had he approval of the school. The magazine noted that the frequencies generally available were 27.23-27.28 MHz., 460-461 MHz, 462.525-467.475 MHz, and 2450-2500 MHz. Power was often (but not always) limited to 5 watts.

While experimental licenses are still provided for in Part 5 of the FCC Rules, there is no specific provision today for student experimental licenses.

1963 Homemade Microphone

We’ve previously shown (here, here, here, and here) other homemade microphones. This idea for a carbon mike appeared in Electronics Illustrated, September 1963. The mike element itself is made of carbon granules. These are obtained by cutting open an old carbon-zinc battery and removing the carbon rod.
You grind them up finely with a file, or by using a metal rod as a rolling pin. The resulting granules are placed in a plastic bottle cap, and wired to a battery and transformer. Almost any type of transformer can be used, either an audio transformer or power transformer. The larger winding is connected to the mike element. The cap is set on top of a paper tube 2-3 inches in diameter, into which you speak.

1963 Science Fair Ideas

If Junior is looking for ideas for the science fair, here are some oldies but goodies, from the August 1963 issue of Boys’ Life. Any of these will certainly earn Junior a nice participation ribbon. But if you’re looking for more spectacular ideas, some of which are very easy, and some of which are very complicated, be sure to check out our full category of Science Fair Ideas.

Last Minute Science Fair Ideas

If you’re getting ready to go to bed, and Junior just remembered that the science fair project is due tomorrow, there’s no need to panic. Any of the projects on this page will provide a suitable demonstration of some scientific principle, and you–er, I mean Junior–can whip them together in a few minutes with materials found around the house.

The first one, shown at right, demonstrates static electricity. A glass jar with a metal cap contains a few bits of tissue paper, and Junior can make them “dance” without moving the jar. This is done by shuffling his feet along the carpet to get an electric charge. Instead of touching an unsuspected family member as he would usually do, he touches the lid of the jar. This causes the paper to be attracted and leap from the bottom of the jar.

The next experiment, shown at the top of the page. demonstrates the relationship between magnetism and electricity. A closed coil of copper wire is suspended next to a magnet. Another magnet is moved inside the coil. The magnet induces a current in the coil, which causes the coil to become an electromagnet. It is then repelled from the hanging magnet.

The third experiment, at left, demonstrates indirectly the acceleration due to gravity. A liquid is poured, and it is noted that the column becomes thinner toward the bottom. This is because the liquid is moving faster at the bottom.

Finally, Junior can demonstrate the concept of surface tension with the experiment shown below. A cork is carefully connected to a metal ring, and placed in a cup of water so that the cork is just barely submerged by the surface tension of the water. When a bar of soap is touched to the water, the surface tension is reduced, and the cork pops to the surface.

The science teacher will be suitably impressed, and won’t have any idea that the experiments actually came out of the May, 1943, issue of Popular Science.

UFOs and IFOs by Gardner Soule

I recall checking out the book shown here, UFOs and IFOs: A Factual Report on Flying Saucers, by Gardner Soule, from the library in my elementary school. Looking at the reviews on Amazon, it looks like this particular tome made its way into a lot of elementary school libraries. In any event, it was a scholarly look at the UFO phenomenon, and since it was presumably vetted by the school librarian, it must have been real science.

The author was a fairly prolific writer about topics that we might today call the paranormal. He specialized in cryptozoology, and according to Wikipedia, his most famous work was Maybe Monsters. (But in my opinion, UFOs and IFOs was the most popular.) He specialized in books for young readers, and his works appeared in Boys’ Life and Popular Science.

The main thing I remember from this book, though, was his advice as to preparing for encountering a UFO. If you happened to be in a position to observe a UFO, then it was more or less an obligation that you would use the opportunity to gather data for use by the scientific community. I believe that one item he recommended that you carry with you at all times was a small compass, so that you could report back to the scientists any magnetic activity from the UFO. But the specific recommendation that I remember was that you carry with you at all times a diffraction grating. Armed with this, you would be able to determine the spectrum of light from the craft. Scientists would then be able to use this information to ascertain the materials used in the craft.

I forget whether I took to carrying a compass with me, but I never did figure out how to get my hands on a diffraction grating for my everyday carry. Thankfully, they’re easy to find these days.

If you see a UFO, and don’t have a diffraction grating in your pocket, you’re going to feel embarrassed, especially since we gave you this reminder. The scientists won’t be happy. Therefore, we recommend that you order one immediately. Fortunately, they are now available at our sister site, MyEclipseGlasses.com, for only $3.99, which includes free shipping anywhere in the world.

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1973 National Scout Jamboree Arts & Sciences Competition

I remember seeing this notice (or possibly one like it from another source) fifty years ago in the March 1973 issue of Boys’ Life magazine.

As an aspiring scientist and Tenderfoot Scout, I was, of course interested in this opportunity to showcase my scientific knowledge before a national audience. The quadrennial National Scout Jamboree was to take place that year, and I was going. Normally, mere 12-year-old Tenderfoots did not participate in this event, but 1973 was an exception. That year, the Jamboree was being held at two separate locations, in Pennsylvania and Idaho. 1973 was the only year it was split that way. And 1973 also had the distinction of being open to regular troops. Normally, individual scouts sign up and are assigned to a provisional Jamboree troop. But in 1973 the BSA made the good decision, never repeated unfortunately, to open it up to all scouts to attend along with their normal troop and leaders. (Among the other events was the “wide game”, about which I’ve previously written.)

By March of that year, we were already signed up, and this announcement showed another opportunity. The Jamboree was to host an “Arts and Sciences” competition–a science fair combined with an art exposition. I don’t even remember the art part of the event, but I did sign up right away for the science fair. My exhibit was Atomic Energy, and I cobbled together a few interesting objects to put on display on my assigned 2-1/2 by 4 foot table. I remember borrowing a Geiger counter from the county civil defense department, and I had an illustrated brochure from the Monticello nuclear power plant. It was set up in a tent somewhere on the Jamboree grounds. After setting it up, I did visit a couple of times, although there wasn’t a lot of traffic.

I didn’t come home with a blue ribbon, but I did earn a red ribbon. In retrospect, it was probably a participation trophy, but it’s still a prized possession. Interestingly, this was before I got my ham license, and I never did run into KJ7BSA, the Jamboree’s special event station.

Science Fair Ideas: Fun With a Homemade Galvanometer

Eighty years ago, there was a war going on, but that didn’t stop young scientists on the home front from conducting experiments with the items available. If Junior’s science fair project is due tomorrow, he can take a cue, and whip together a great project from these ideas in the December 1942 issue of Popular Science.

Both experiments involve a galvanometer, and the magazine presupposes that young scientists know how to make one, because the instructions merely state to use “your homemade galvanometer.” But in case Junior doesn’t know, it’s easy enough. You just take a compass (a toy one from the dollar store will work just fine) and wrap a few turns of wire around it. The smallest of electric currents will cause the compass to move. If there’s a little extra time before the science fair, we’ve previously shown how to make a deluxe galvanometer.

In the first experiment, shown above, Junior can demonstrate that water, contrary to popular opinion, is an insulator. It’s only when a little bit of salt is added to the water that it starts to conduct electricity, and the compass moves. To accentuate the effect, we recommend starting with distilled water. And don’t worry about not being able to find the old-fashioned dry cell batteries. These experiments will work just as well with modern alkaline D cells, especially if you purchase battery holders for them.

The second experiment, shown below, shows how to make a thermocouple. Two pieces of wire–copper and iron (or steel)–are twisted together. When the twisted wires are put into a flame of a candle, the dissimilar metals produce an electric current, as shown by a movement of the compass. And as we always remind parents about experiments involving flames, don’t forget to give Junior a box of matches!

As with many of our projects, Junior is almost guaranteed to take home the blue ribbon, and the teacher won’t have a clue that the project was put off until the last minute.

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1937 Disco Ball

What we know as the “disco ball” has a long heritage, as shown by this depiction 85 years ago in the December 1937 issue of Popular Science. The magazine featured a number of ideas on what to do with a broken mirror, and assured readers that it needn’t signify seven years of bad luck.

The magazine noted that one use was to provide spectacular color effects for parties and dances. This was done by focusing colored spotlights on a mirror-covered globe. This was made by cementing small squares of mirror on a large ball or toy globe. This was attached to a spindle which could be spun by hand or with a small geared-down motor.

According to Wikipedia, what is now known as the disco ball dates back to 1917.

If you have a piece of mirror left over after making your disco ball, you can mystify your friends with the magic trick shown below:

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