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This Week's Experiment - #478 Batteries?

I wrote this week's experiment while I was writing an electricity manual for the Memphis Pink Palace Museum's Suitcase Outreach program. Usually I try to stick to everyday language instead of using technical terms when I write the Experiment of the Week. That gets me quite a few email saying that technically I should use "mass" instead of "weight", "NaCl" instead of salt, and so on. This week, I am going to get technical to help show you some interesting things. To try this, you will need:

pliers
a 9 volt battery
battery powered devices around your house

First, look around at some of the things in your house that run on batteries. What if I told you that some of them really do not run on batteries? It would be true, but only on a technicality.

The first battery was invented by Alessandro Volta, back in the year 1800. He found that by using a disc of zinc and a disc of copper with a piece of cloth soaked in salt water placed between them, he could produce a current of electricity. You might have seen similar experiments where you stick a piece of copper and a piece of zinc into a lemon to produce electricity. Volta found that one cell did not produce much electricity, but by stacking several cells, he could combine their voltage (which is named after Volta). The more cells he stacked, the more voltage he got. That stack of cells was the first battery.

That is where our technicality comes in. Technically, a battery has to have two or more cells. When you look at AA, AAA, C and D "batteries", you find that each of them is really a single cell. That means that if you have a small flashlight that only takes one of these, it runs on a cell, not on a battery. Of course, if your flashlight uses 2 D cells, then you have a battery, since the total is 2 cells.

OK, so I am splitting hairs a bit, but there is a good reason. The most voltage that you can get out of a modern electric cell is 1.5 volts. If you look at the voltage on AA, AAA, C and D cells, you will find that all of them produce 1.5 volts (unless they are rechargeable, which usually only produce 1.2 volts) If you find a "battery" that produces more than 1.5 volts, then it probably really is a battery, containing 2 or more cells.

Now, lets look at our 9 volt battery. Because it produced 9 volts, we can be pretty sure that it actually is a battery. Before we check, lets do some math.

Math! Wait a minute! No one said anything about me having to do math! Well, this is simple math, so I guess it is OK. We are going to calculate how many cells the battery has. Let's start with 1.5 volts for one cell. Adding another cell will add the voltages, so we will have 3 volts. If two cells give us 3 volts then 4 cells should give us 6 volts, and that means that to get 9 volts we would need six cells.

Let's check and see if that is correct. Look at the top of the 9 volt battery. It has two electrical contacts on its top. The sides are metal, and bend inwards to hold the top in place. CAREFULLY use the pliers to bend the metal sides away from the top. Be very careful, as the metal edge may be sharp. When you bend the sides enough, you should be able to remove the top. What do you see inside? 6 small electric cells. They look like AAA cells, but they are even smaller. Our math was correct.

You can do the same thing with other batteries. What about one of the large, square, 6 volt lantern batteries? How many cells would it have? Four, right? Right. If you open one, you will find....four D cells. Most car batteries are 12 volts. How many cells would that be? Do the math, and then look at your car battery. You should be able to see evidence that it has 8 cells, which will total to 12 volts.

So you see, there are times when it helps to use the technical jargon. Now I am off for a bowl of ice cream, which will probably cause me to gain some mass.

Have a wonder filled week!

This Week's Experiment - #479 High Bounce

Be sure to try this science experiment outside! It will save you the work of cleaning up the pieces of broken lamps and shattered windows.

For this experiment you will need:

a basketball or soccer ball
a tennis ball
duct or masking tape
a flat, hard surface, outside

Hold the basket ball about shoulder high in one hand and the tennis ball at the same height with the other. Drop both at the same time. If both are fairly new and fully inflated, they should bounce about the same height. OK, nothing strange about that.

Next, use the tape to make a round, raised collar on the basketball. This is going to help you balance the tennis ball on top of the basketball. It does not have to be fancy. Just a ridge of tape in a circle that will fit the bottom of the tennis ball.

Hold the basketball out at the same height as before, with the tape ring at the top. Place the tennis ball into the tape ring. It should balance there. Now, before you drop it, think about what you expect to happen. Then drop the balls.

Understanding the Science

What happened? The tennis ball bounced VERY high. Why did that happen?

When you were holding the basketball and the tennis ball, they had potential energy, the energy of position. When you released them, that potential energy was changed into the energy of motion. In other words, they fell. When the basketball hit the ground, its momentum compressed it, flattening the bottom. The same thing happened when the tennis ball hit the basketball. Their energy of motion was changed into compressed mechanical energy, much like squeezing a spring.

Then the compressed mechanical energy was changed back into the energy of motion. As the basket ball bounced, it bumped into the tennis. That impact transferred some of the energy of motion from the basketball to the tennis ball. The basketball was left with less energy of motion, so it did not bounce as high as it did the first time. The tennis ball wound up with a lot more energy of motion, so it bounced very high.

What do you think would happen if you reversed the two balls, putting the basketball on the top? How much higher would the extra energy from the tennis ball lift it. What if you used a heavier ball instead of the basketball? Or a ping pong ball on the top? There are all sorts of combinations to try, and you will be surprised how much you learn while you are having fun.

Have a wonder-filled week!

This Weeks Experiment - Heating a Balloon
Taken from the original version of experiment #13, written May 15, 1997.

You can see the video version of this experiment at:
http://www.krampf.com/experiment_vid.html

*WARNING* This experiment uses fire. Be safe, use common sense, and be sure there is an adult in the room, so you have someone to blame if something goes wrong.

This is a variation of an old, Victorian parlor trick, but even after more than 100 years, it is still just as amazing. In Victorian times, the experiment was done by folding a calling card (much like a modern business card) into a square container. When the paper container was filled with water, it could be held over a candle to boil the water without the paper catching fire.

For this modern version, you will need:

a candle
matches or a lighter
several balloons
water

Blow up one of the balloons and tie it off. Light the candle. Now, what do you think would happen if you held the balloon in the candle flame? Lets try it and see. Carefully, hold the balloon just at the top of the candle flame. BANG! Just as you probably predicted, the balloon pops and it blows out the candle.

Now, lets try that again, but this time with a twist. Instead of filling the balloon with air, lets make it a little more fun. Lets try the experiment with a water balloon! Carefully stretch the mouth of the balloon over a water faucet and slowly fill the balloon with water. Then blow in a little air and tie it off.

At this point, work over a sink or outside, just in case things don't work as they should. Once again, light the candle, and hold the balloon over the candle, just at the top of the flame. What happens? You probably expected the balloon to pop, getting you wet. Instead, the bottom of the balloon turned black, but it did not pop. Why?

Understanding the Science
Water is very good at soaking up heat. Because the balloon is very thin, heat energy passes through it quickly heating the water on the inside. As the water near the flame starts to get hot, it rises, letting cooler water take its place to soak up more heat. This process lets the water balloon absorb a tremendous amount of heat without popping.

The black stuff on the balloon is the element carbon. It did not come from the balloon. Instead, it was deposited by the candle flame. The balloon has not been burned or damaged.

The idea of absorbing heat to control it is a very useful idea indeed. Firefighters use it to protect themselves while they are fighting fires. The radiator in your car absorbs heat from the engine to keep it from overheating. Heat sinks in computers absorb heat to protect delicate circuits. The idea even applies to ice cream, which absorbs the heat from hot fudge sauce, cooling it enough so you can eat it without burning your mouth. That sounds like an experiment worth trying.

Have a wonder-filled week!

Robert Krampf's Experiment of the Week: #483 Why Wet Things Don't Burn?

This week's experiment was inspired by my recent science video about how to hold a balloon in a candle flame without popping it. It started me thinking about why water is so effective at stopping fires.

*WARNING* This experiment involves the use of fire. Be safe, and be sure that there is an adult with you to help.

To try this, you will need:

paper towels
kitchen tongs or pliers
a lit candle or a lighter
a bowl of water

Begin by tearing a strip of paper towel about an inch wide and a couple of inches long. Hold it in the tongs and place it over the flame of the lighter. What happens? It quickly catches fire, just as you would expect. Put the burning paper into the water to put out the flames.

Then tear another strip of paper towel the same size. Hold it with the tongs, but this time dip in into the water first. Once it is wet, hold it in the flame. What happens this time? The paper turns black, but it does not burn. Even the black color does not come from the paper. Instead, it is carbon soot that comes from the flame. As long as the paper is wet, it will not burn. Why?

Understanding the Science

Some things are so common that we just accept them without wondering why. Water puts out fires, so of course wet things don't burn. But why? There are several things that add together to give water its fire quenching ability.

First, water does not burn. Why not? After all, it is made up of hydrogen and oxygen, both very flammable gases. When you burn fuel, it combines with oxygen. Last week, we saw that when we burned iron, it bonded with oxygen to become iron oxide. The carbon found in many fuels will bond with oxygen to become carbon dioxide. The hydrogen in water is already bonded to oxygen, so it is the same as if it had already been burned.

Second, water absorbs a lot of heat. Every material has a property known as specific heat. That is the amount of energy that it takes to raise the temperature of one gram by one degree. Water has a high specific heat, which means that it can absorb a lot of heat energy before it gets hot enough to boil. At the point where it boils, it absorbs even more heat, to give the molecules enough energy to change from a liquid to a gas. With the water absorbing all that heat, the wet fuel does not get enough heat for it to burn. That is how the balloon in the video was protected from the flame. It is only when the water has evaporated that the fuel can finally get hot enough to catch fire.

Water also separates the fuel from the oxygen it needs to burn. A coating of water provides a barrier to keep oxygen away from the fuel. Without that oxygen, the fuel won't burn.

All these things combine to explain why wet things don't burn.

Safety
With that said, it is important to mention that there are some fires that you should never use water on.

Never put water on an electrical fire. Water conducts electricity, and it could provide a connection between you and the electric wires.

Never use water on grease or oil fires. Water is heavier than the oil, so instead of floating on top, where it would block the oxygen, it sinks to the bottom. There it absorbs enough heat to change into steam. The rapidly expanding steam throws the burning oil in all directions, spreading the fire instead of putting it out.

That is why you should always have an approved type ABC fire extinguisher in your kitchen. They are inexpensive and can save your kitchen and your life.

Have a wonder-filled week!

Robert Krampf's Experiment of the Week:
#492 Building a Nest

This week's experiment is one that we used for teaching about birds back when I worked in the Education Department at the Memphis Pink Palace Museum. On our trip, we went by to say Hi to old friends, which brought back tons of great memories. This is one of the fun things my brain dredged up.

Look at some bird nests. You can either search your yard ( just look, don't touch or bother the nest), visit your local Nature Center, or search the Internet. A quick Google Image search for "bird nest" came up with over 175,000 images of bird nests. Look at the wide variety of nests, from huge Bald Eagle nests that can weigh more than a ton, to the marvelous nests that Hummingbirds build from spider webs. They truly are amazing, but how hard are they to build. That is what we will find out.

To try this, you will need:

Tweezers
several marbles
sticks
grass
string
leaves
hair
other things you may find in your yard

OK, the task is simple. Collect your materials from the yard, and then try to build a bird nest. You can select from anything in your yard that a bird might use. Think about the different nests you have seen, and what they were made of. Sounds like an easy project, right? Oh, one more thing. You have to collect the materials and build the nest using the tweezers. Birds don't have hands, and most of them make very little use of their feet in nest building. For most birds, their single tool is their beak. You don't have a beak, so you get to use the tweezers instead.

Your goal is to make a nest that would sit in a tree or a bush, and that would hold several bird eggs, or in our case, glass marbles. Trees and bushes are exposed to the wind, so the nest has to be sturdy enough so that it will hold the marbles, even when you shake the nest to simulate wind blowing the bush. You are limited to materials a bird would use. That rules out wrapping your nest in Duct tape or using glue to hold it together. Some birds do use their sticky saliva as a glue to hold the nest in place. In fact, nests made from the saliva of certain cave swifts are used to make Birds Nest Soup, a Chinese delicacy. Yum! I love Birds Nest Soup, even though I know it is made of bird spit. Feel free to use spit on your nest, if you think that will help.

When you are done with your nest, test it with the marbles and some gentle shaking. If it holds together, congratulations! Take a photo and email it to me. I will post the nests on my blog (http://www.thehappyscientist.com). Be sure to send your name, age, and what materials you used, to post with your nest photo.

When you are done, look back over the photos of the bird nests. You should then have a true appreciation of the skill these amazing creatures have, to build such elaborate structures with just their beak. Imagine trading in your hands for a beak. Just imagine how much work it would be to eat an entire bowl of ice cream with just a beak! Now that is something worth experimenting with!

Have a wonder-filled week!

Robert Krampf's Experiment of the Week:
#496 Which is the Magnet?
********************
This week's experiment is a fun science puzzle involving magnets. To try it, you will need:

a strong magnet (available at most hardware stores)
three paper clips

Straighten two of the paper clips, so that you have two long, fairly straight pieces of wire. Get both as straight as you can. Place one aside. Hold the other, and rub one end of the magnet along the paper clip, starting at your finger, and moving to the other end. Move the magnet away from the metal and repeat the process. Keep stroking the magnet along the paper clip, always in the same direction, for about 40 strokes. By doing this, we are magnetizing the paper clip.

Test the magnetized paper clip by bringing one end of it near the extra paper clip, the one that you did not straighten. If your paper clip is magnetized enough, it should attract the other clip. If not, try again with the procedure above.

Once you have the paper clip magnetized, you are ready for the challenge. Put both of the straightened paper clips together. Mix them until you are not sure which is which. The challenge is to figure out which one is the magnet and which is not, but you cannot use ANYTHING else to test with. No fair using the third paper clip, iron filings, a compass, or anything else. You are also not allowed to break the paper clips. The two straightened clips are all you need to figure it out.

So, how do you find out which is which? If I told you, you would just say, "Oh that makes sense." instead of really trying it. If you are really patient, you could wait until next week for the answer, but I bet you have enough scientific curiosity to actually get the materials and try it yourself.

Have a wonder-filled week!

Krampf je na http://www.krampf.com/

Poučan topic

Saradadevii, baš mi je Krampf trebao :)

Jučer sam s Markom palila različite materijale da mu pokažem razliku između prirodnih materijala i plastike.

Nešto za prvačiće. Kopiram jedan radni listić:

JE LI LAKŠE PLIVATI U SLATKOJ ILI MORSKOJ VODI?
Materijal i pribor: 2 čaše, topla voda, sol, žličica, 1 jaje

Postupci pri radu:
1.Ulij vodu koju piješ do polovice čaše. Kakvog je okusa voda koju pijemo?
2.Stavi jaje u tu čašu s vodom koju piješ. Što se događa?
3.Ulij u drugu čašu vodu i stavi u nju više žličica soli i promiješaj. Kakvog je okusa ta voda?
4.Stavi jaje u tu čašu sa slanom vodom. Što se događa?
5.Nacrtaj svoje istraživanje.

Opažanje:
Kada jaje tone, a kada pluta?
Zaključak:
Što zaključuješ, je li lakše plivati u morskoj ili slatkoj vodi? Zašto?


LJETO JE, KAKO SE ODJENUTI?

Materijal i pribor: crni papir, bijeli papir, gumice, 2 čaše, voda

Postupci pri radu:
1.Omotaj jednu čašu bijelim papirom i pričvrsti ga gumicom.
2.Omotaj drugu čašu crnim papirom i pričvrsti ga gumicom.
3.Obje čaše napuni vodom tako da ne smočiš papir.
4.Ostavi čaše na mjestu gdje ima mnogo sunca 2 sata.
5.Nakon 2 sata prstom probaj koja je voda toplija.
6.Nacrtaj svoje istraživanje.

Opažanje:
Koja je voda toplija?
Koji je papir privukao više sunca i topline?
Zaključak:
Koje bi boje trebala biti naša odjeća da nam ne bude vruće?

ajmo HOP... dosta je bilo odmora...

ovo je bila dobra tema i one koji imaju ovakve super ideje pozivam da nastave pisati... sad kad smo se vratili u školu... :)