Category Archives: Science fair ideas

Science Fair Project: Electricity Through Glass

If you’re looking for an interesting but slightly dangerous experiment for your science fair project, you’ve come to the right place, with this project from the August 1938 issue of Popular Science. With just a few odds and ends from the hardware store, you’ll be able to cause an electric current to flow through glass.

You’ll need some copper wire (which can be cannibalized from the electric light you’ll be using, as well as some glass tubes. If you can’t find the glass tubing locally (or “borrow” a couple from your science teacher), then one of the least expensive options appears to be these reusable glass drinking straws from Amazon or these glass test tubes.

You’ll need a lamp cord similar to the one shown here, or you can simply use a normal desk lamp. Cut one of the two wires leading to the lamp (or plug it into an extension cord and cut one of those two wires), and strip the insulation off the end of the two wires. Insert each wire into a glass tube.

Of course, glass is an insulator, so the lamp won’t work when plugged in. But when you hold the two glass tubes next to each other and heat them in a bunsen burner, electricity will begin arcing through the molten glass, and the light will come on.

It appears that what’s happening is that an oxide of the copper is mixing with the molten glass, and the current is using this as an electrical path. When you remove the glass from the flame, the light will stay lit until the glass again solidifies.

Warning: This experiment uses household electricity, which can kill you if you’re not careful. Don’t work in a wet area or anyplace where you can touch a metal object. Whatever you do, don’t let anyone touch either of the two exposed wires. When you’re done with the experiment, cut the plug off your modified cord so that some younger kid won’t plug it in and get electrocuted. Do this experiment only with adult supervision.

1978 Solar Oven

Forty years ago this month, the August 1978 issue of Boys’ Life carried these plans for a solar oven. According to the magazine, the oven would reach 200 degrees, “hot enough to cook a meat loaf or bake breads in several hours.” The inner and outer boxes were insulated with fiberglass insulation and sealed air tight. The inside of the inner box was painted black with a “non-lead” paint. Four shiny aluminum panels could be used to direct heat into the oven.

A suggested improvement to increase efficiency was to use a double layer of glass with an air gap between the two panes.

If you would prefer to have someone else do the construction work, the solar oven shown at left is you can find this solar oven Amazon which appears to have good reviews.

1968 Radio Shack Battery Kit

Fifty years ago, the August 1968 issue of Radio-TV Experimenter showed this interesting offering from Radio Shack, a hobbyist kit for assembling two D-cell flashlight batteries.

By all appearances, the finished product is identical to the store’s pre-manufactured “heavy duty” carbon-zinc battery. The only difference is the price, as you apparently had to pay a small premium for the privilege of putting it together yourself: The kit cost $1.25 for two batteries, but the manufactured article, as shown below in the 1968 Radio Shack catalog, were available four for 98 cents.

Despite the slight extra charge, there is something alluring about making a product at home that’s indistinguishable from the factory version (as is the case with this currently available AM-FM radio kit). For students thinking about making a homemade battery today, see our earlier post about making a reasonably useful battery suitable for emergency use, or this hundred year old idea for making a homemade flashlight, battery and all.

1938 Pyro Pantagraph

This ad for the Pyro Pantagraph appeared 80 years ago this month in the August 1938 issue of Radio Craft. For a mere $2.75, the enterprising young man or woman could go into business and “burn your way to extra dollars.” The burning tool was designed to burn designs onto leather, wood, cork, bakelite, or even gourds. The electric pencil plugged in to any 110 volt outlet, with “plug and cord furnished as part of equipment.”

Pantograph. Wikipedia animation.

But what made the set special was the pantograph, which allowed designs to be reproduced in the original size, enlarged, or reduced, as illustrated by the animation here.

As far as I know, the Pyro Pantagraph is no longer available, but inexpensive wood burning tools such as the one shown here are readily available, as is a pantograph such as this one. Most modern pantographs appear to be made of plastic, so you’ll need to figure out a way to affix the burning tool. And most of the negative Amazon reviews are fixated on the fact that the instructions are in Chinese. But we’re confident that our readers are smart enough to figure these things out themselves, and have no need for the instructions. You can still burn your way to extra dollars, or this could be the basis for a most interesting science fair project.

More Planning Advice for Time Travelers

Admittedly it’s unlikely that you’ll need the information, but we occasionally provide useful advice to keep in mind in case you’re ever inadvertently subjected to time travel. If you get caught in a time warp, the experience will be much less unpleasant if you do some minimal preparation.

For example, if you get sent back to the past, your situation would be much improved if you could “invent” some modern technology. Columbus could use some better navigational tools to determine that he had not, in fact, reached India. Louis XVI would have been more likely to keep his head with a telegraph to better manage the affairs of his kingdom. Just about wherever and whenever you arrive, you’ll have similar opportunities involving people who would be willing to pay handsomely for bits of technology that you can invent.

We’ve previously written about the importance of having a WikiReader, which holds the contents of the English Wikipedia in a handheld device. And we’ve written about how to make the most difficult component of a radio receiver, the earphone, from scratch.

We’re confident that most of our readers will do well if they’re ever whisked back into time.

How to Figure Out the Date

In many situations, you’ll be able to determine the date easily. If you’re in an urban area in the past few centuries, you can simply peek at a newspaper. You can even ask people on the street what year it is. They might give you a funny look, but if more than one person gives you the same answer, it’s a safe bet that they’re telling the truth. If they’re not clear on the concept of the A.D. scale, then you can determine things such as the name of the king, and use your WikiReader to figure out the year.

But in some cases, this information might not be quite so convenient. Fortunately, the night sky provides a convenient clock, and with a bit of number crunching, you should be able to figure out the date.

Determining the Day of the Year

The first step is to determine the day of the year, and this is quite easy. You simply observe the local sunrise and sunset times. The sunrise and sunset times will be the same from year to year, so you can use a reference for any year. Just note the time of sunrise and sunset, and see which day they correspond with. You’ll probably come up with two possible dates, so you might need to check again to see whether the days are getting longer or shorter. In the Northern Hemisphere, if the days are getting longer, then the date is after December 21 but before June 21. If the days are getting shorter, then it’s after June 21 but before December 21. The best source of sunrise and sunset times is probably the Old Farmer’s Almanac, although this information should be available in many places. You can probably find it somewhere on your WikiReader. Remember, the year of your source is unimportant, since the data will be about the same from year to year.

Determining the Year

The planets. NASA image.

Now that you know the month and day, you can move to the next step, namely, figuring out what year it is. For this, you can use the planets. The planets Mercury, Venus, Mars, Jupiter, and Saturn are all visible to the naked eye. On any given date, each one of them is supposed to be in a particular spot in the sky, in one of the twelve constellations of the zodiac. You start by finding these planets and noting what constellation they are in.

At this point, you can go to a website such as Your Sky, start punching in the various possible dates, and see which one corresponds to the observed data. When you get a match, you know the exact date, at least within a few days. For example, currently (1 August 2018), Mercury is in Cancer, Venus is halfway between Leo and Virgo, Mars is right between Capricorn and Sagittarius, Jupiter is in Libra, and Saturn is between Scorpio and Sagittarius.

So if I knew it was August 1, I would simply use that date, and repeat the process with different years until I found that the planets matched up with what I was seeing in the sky. In this case, as soon as I plugged in 2018, I would see that it matched, and know that I guessed the year correctly.

How To Do This Without the Internet

Of course, I’m sure that by now you’ve spotted a big flaw in this strategy. If you have the internet available, then you can just ask the internet what date it is. But that website, and others like it, merely employ a relatively simple computer program. You can find all of the information you need to calculate the same positions by using a book such as Practical Astronomy With Your Calculator or Spreadsheet. It will contain all of the information you need to do the calculations, either with a calculator or computer, or if all else fails, with pencil and paper. You can buy the book now, before the time warp.

On the other hand, you’re probably thinking that the likelihood of needing such a book is quite small. If you don’t get stuck in a time warp, then it’s money wasted, and I would have a hard time arguing with you. In fact, if you get sent back along with a public library, you’ll probably be able to find a similar book there.

You’ll want to use the full size version of this chart, which is available, along with complete instructions, at this link.

But there’s still a minimal level of preparation with practically zero cost! I found this homework assignment from a college astronomy course. If you print this out before getting sent back in time, it actually includes all the information you will need to calculate the positions of the five visible planets! It uses a graphical method: Right there on the worksheet it gives the position of the planets as of a certain date. You simply calculate how many times each planet will need to go around to reach that date. After you do the division, the remainder is the portion of one orbit the planet is away from that spot. You plot the position of both that planet and the Earth on the provided graph, and you can then see where in the sky the planet is located on a given date.

This method is not as precise as the computer programs, but those computer programs are designed to show you exactly where to point your telescope. You don’t need that level of precision. By graphing the general location of several planets, you will be able to confirm what year it is.

You should download (or better yet, print) that worksheet now, before the time warp.

Checking Your Work

To confirm that you’ve picked the correct year, you might want to use another method. It’s possible, for example, that all of the planets were in the same position in the sky on today’s date millions of years ago. The best way to check your work is to use the precession of the equinoxes. Simply put, the star Polaris is currently located at the North Celestial Pole. In other words, all of the stars in the sky seem to revolve around this point. But the celestial pole moves over time, following a 26,000 year cycle. You’ll want to print the handy chart shown here. Match up the pole star with the chart, and you’ll know where you are in the cycle. For example, if you discover that Vega is the pole star, that means the year is approximately 11,000 BC (or maybe 12,000 AD).

Flame Speaker Science Fair Project

For the aspiring mad scientist looking for a spectacular science project that combines fire, high voltage, and loud noise, the flame speaker described in the July-August 1968 issue of Elementary Electronics should fit the bill perfectly. We previously written about how a flame can serve as a radio detector. As this article shows, it can also serve as the speaker, as the flame can be induced to emit sound. Depending on how much work you want to do, the quality of the sound can be extremely good. But even a modest investment of time can make the flame produce sound, although the simpler setups will be somewhat distorted.

The general principle is quite simple. The flame constitutes a plasma, often referred to as the fourth state of matter, made up of a cloud of positively charged atoms and free electrons. When an audio frequency signal is applied to the plasma, the positive ions and electrons move, creating a bending of the flame and room-filling sound.

The simplest arrangement is shown here. The output of an audio amplifier is fed to a transformer to step up the voltage. Nearly any transformer can be used. In this case, a bell transformer–ordinarily used to step-down 120 volts to 6 volts–is hooked up in reverse. Such a transformer can be found inexpensively on Amazon, but it’s probably possible to scavenge one. A trip to the local thrift store will probably allow you to find a “wall wart” power supply. If you can find one with an output of about 6 volts ac, then your work is done. If you can only find one with a DC output, then you’ll need to open it up and remove the rectifier.

The transformer increases the voltage of the audio sufficiently to modulate the flame. This output is connected to two electrodes, in the form or ordinary nails, which are inserted into the flame.

The flame can come from a variety of sources. The higher the temperature the better, but the author was able to produce sound with as little as a single candle. Various types of torches, or even a bunsen burner, can also be used to produce more sound. An inexpensive butane torch would probably prove most adequate, or you can use an inexpensive propane torch such as the one shown here.

The ordinary combustion products do not provide sufficient plasma, so it is necessary to insert some potassium nitrate into the flame. The article recommends using an asbestos wick, in the form of “asbestos tape used to seal pipe joints in warm-air heating systems.” If you can’t find the potassium nitrate locally, it’s inexpensive on Amazon.

Of course, asbestos can’t be used today, since it would result in the haz-mat team immediately shutting down the science fair. But the article reveals that the potassium nitrate is in a solution of water, meaning that even a combustible wick would probably survive all but the hottest flames, at least long enough to do the experiment. So it seems that a normal wick, such as used in a kerosene lamp, would be more than adequate. Indeed, with some experimentation, it would seem that almost any kind of fabric could be used, as long as it begins the experiment saturated with water. Another option would be the use of welding fabric.

More advanced students will want to get rid of the distortion inherent in the simple design, and this can easily be done by providing a bias voltage. The article recommends about 400 volts. Other improvements include replacing the nails with tungsten or nichrome wire, and recommends sources. You can scavenge the nichrome wire from an old toaster, or buy it inexpensively on Amazon. The article recommends, of course, that proper precautions be taken if the high voltage bias is used. With the original simple setup, however, the experiment should be relatively safe, since no high DC voltages are used.

The original article is available from this link. Even the simplest version of this experiment is certain to take home a blue ribbon, and the more advanced version could produce truly spectacular results as the flame changes color and pulsates as it produces room-filling sound. The kid with the potato clock won’t stand a chance. You can derive some inspiration from this and other videos of flame speakers:

Balancing Act

Seventy-five years ago this month, the June 1943 issue of Popular Science showed how to do this seemingly impossible balancing act. The hammer is suspended by a string in the middle, with the end of the handle exerting an upward force on the end of the ruler. Since the center of gravity is under the table, the ruler stays in place.

This simple stunt could be the basis for an elegantly simple science fair project regarding leverage.

Science Fair Project: Magnetic Lines of Force

If you’re reading this page because Junior just remembered that the science fair project needs to be handed in tomorrow, there’s no need to panic! This site is full of interesting science fair projects. Some of those projects might take some time to complete, but many of them can be whipped into shape in an evening. This one falls into that category. Junior can make an impressive display by mapping magnetic lines of force.

If the project is due tomorrow, have Junior start reading the Wikipedia article about magnetic lines of force. In the meantime, you can race to the hardware store or dollar store to get the items he’ll need, if you don’t have them already.

First, you’ll need some insulated wire. Any kind of wire will work, as long as it’s insulated. At the dollar store, you can probably find it in the electronics aisle in the form of speaker wire. Get about 10-20 feet.

You’ll also need a battery. The old-fashioned dry cells shown above look nice, but there’s really no need. Normal D-cell flashlight batteries will work just fine. Get a few extras, since they will be used up quickly.

Finally, you’ll need a cheap compass. If you don’t have one already, you can probably find one in the toy department, and it will work fine. And while you’re there, don’t forget to get the obligatory poster board, markers, etc.

Have junior construct the loop of wire shown in the picture, and embed it in a piece of cardboard. Hook the ends of the wire to the battery, and you have created an electromagnet. Simply move the compass around the cardboard, and with a pencil, make a small mark showing what direction the compass is pointing. Connect all of these marks, and you will have an accurate diagram of the magnetic lines of force.

The teacher will be impressed, Junior will get a blue ribbon, and nobody will know that he waited until the last minute.

You can find more details in the March 1943 issue of Popular Science, from which the illustration was taken.

1943 Test Equipment

One item that was in short supply 75 years ago were meter movements. There was a backlog in their manufacture to the point where hams were being encouraged to sell their old ones, as shown from the form at left from the April 1942 issue of QST.

But the absence of a meter didn’t have to mean that it was impossible to measure things. The device shown above was a simple bridge circuit for measuring the values of resistors, capacitors, and inductors. The circuit was contained in an article in the March 1943 issue of QST, submitted by W.J. Mertz, VE4UN, using whatever was available. An audio signal is fed into the input, and the potentiometer adusted until the circuit is in balance, at which point the audio output disappears. By calibrating the dial with a few known values, the unknown value can be quickly determined.

The author didn’t have an audio oscillator, so he instead used the device by feeding in the squeal from a regenerative receiver. And in the absence of anything else to make the dial pointer, he used the handle of a broken toothbrush.

While inexpensive multimeters such as the one shown at the left make this project less necessary today, it could serve as the basis for an interesting science fair project for relatively advanced students. For information about the theory involved, a trip to Wikipedia will provide the necessary background.

1928 Power Supply With Homemade Rectifiers

Tired of the bother and expense of having to buy batteries for his radio, the gentleman shown here is taking matters into his own hands by constructing a B-battery eliminator, following the plans in the March 1928 issue of Popular Mechanics. We showed a 1926 version earlier, and this one is more refined.

In this case, hum is dealt with by electrolytic capacitors, which were available for purchase. Rectifiers, on the other hand, weren’t as easy to come by. But undaunted, he just made his own, consisting of plates of lead and aluminum carefully suspended in pickle jars containing an electrolyte solution. That solution could be borax, sodium bicarbonate, or ammonium phosphate.

The rectifiers were just a bit tricky to get going, which explains the light bulb in series with the transformer primary. If the rectifiers were doing their job, the lamp would light briefly and then dim. If the light remained on, it meant that one of the cells needed attention. In either case, the light bulb served to limit the current and protect the expensive transformer.

Since modern rectifiers are so inexpensive, there’s little practical reason to make your own. However, they’re so simple to construct that a homemade rectifier would probably be the basis of an excellent science fair project for the advanced student.

OneTubeRadio.com

Radio – Emergency Preparedness – Scouting – Law – Politics