Experiment # 10 Conductivity

"Complete a Circuit"

Stuff you need

Battery, size C Piece of aluminum foil, about 4 inches by 12 inches Lightbulb from a flashlight

How to do

Fold aluminum foil several times to make a strip 12 inches long and about 1/2 inch wide

Set the battery on one end of the strip Hold the metal base of the lightbulb to the other end of the battery Touch the metal base of the lightbulb with the aluminim foil strip

Result

The bulb will light up

Why

The aluminum foil strip makes a path for the energy in the battery to follow

The energy follows the path and lights up the bulb

Extra stuff to do

Try different sizes of batteries Try stacking two batteries together Try touching the strip to different places

http://users.stargate.net/~eit/kidspage.htm#circuit

Static Electricity Experiment : Rising Tissue Paper

Materials you will need:

• Scissors• Tissue Paper• Woollen Jumper/Sweater• A Plastic Comb/Pen

This is a magic!

Steps:

1.  Cut up some small pieces of tissue paper.2.  Charge up the comb/pen by rubbing it against a jumper/sweater or combing through your hair about ten times.3.  Hold the comb/pen over the small pieces of tissue paper.

This is a fun experiment to watch as the tissue paper is pulled up by the charged comb/pen.

http://www.kids-science-experiments.com/risingtissuepaper.html

Bloody Current

This spooky bloody current trick will amaze your friends and teach them about ions and electricity. By dissolving household salt in water, ions can move through water. The movement of the ions carries a charge that can illumine a light bulb. Grab the supplies that you need and try this fascinating experiment.

What You'll Need:

Salt Measuring spoons 3 bowls Red food coloring Water Mixing spoon 3 insulated wires (about 5 to 7 inches long), stripped at both ends (ask an adult for help) Flashlight bulb and bulb holder 2 D batteries Tape

© 2007 Publications International, Ltd.Electric Circuit

Step 1: Place about 5 teaspoons salt in one bowl. Put 6 drops red food coloring into 1 tablespoon water in another bowl, and then pour it over the salt. Mix.

Step 2: Set up the electric circuit by referring to the diagram and steps below.

Step 3: Attach wire A and wire B to the two terminals of the light bulb holder (with light bulb attached).

Step 4: Tape the free end of wire B to the positive end of the first battery. Place the other battery's positive end next to the first battery's negative end.

Step 5: Tape wire C to the negative end of the second battery. Be sure batteries are touching each other.

Step 6: Test your circuit by touching the free ends of wires A and C, which should cause the bulb to light. If not, fix your circuit, then go on.

Step 7: Bend the free ends of wires A and C over the third bowl. Fill the bowl with water until the wires are well below the surface of the water. The light bulb will not light because water is a poor conductor of electricity.

Step 8: Now have friends come over. Show them the setup. Ask them if they know who Frankenstein's monster was. The monster was "born" when electricity brought him to life. Show them the red salt, and tell them it is dried monster blood.

Step 9: Pour the red salt into the water, and stir. As the salt dissolves, the light comes on!

How does a motor change electrical energy into motion? An electric current produces a magnetic field. This magnetic field can be attracted to or repelled by a permanent magnet. This attraction or repulsion can cause movement in a wire that carries an electric current.

You will need the following materials:

         1 meter (3 feet) of 22-gauge or 24-gauge solid-core insulated wire                  e.g. Radio Shack catalog # 278-1215         2 disk magnets                  e.g. Radio Shack Catalog # 64-1888         2 insulated test cables with a clip on each end                  e.g. Radio Shack catalog # 278-1157                  (2 pieces of above insulated wire can also be used)         a plastic cup         two large rubber bands         two jumbo size (2-inch) paper clips         D-cell battery         wire strippers         waterproof marking pen         optional holder for D-cell                  e.g. Radio Shack catalog # 270-403

Take the 3-foot piece of insulated wire. Starting about 3 inches from the end of the wire, wrap it seven times around the D-cell battery to form a coil. Wrap the ends of the wire a couple of times around the coil to hold it together.  

Use the wire strippers to remove the insulation from the two ends of the coil.

Straighten the larger loops of two paper clips.      

Turn the cup upside down and place a magnet on top in the center. Attach another magnet inside the cup, directly beneath the original magnet. This will create a stronger magnetic field as well as hold the top magnet in place.

Put two large rubber bands around the base of the cup.

Insert the straightened paper clips into the rubber bands, so they stand upright over the bottom of the cup.

Rest the ends of the coil in the cradles formed by the paper clips. Adjust the height of the paper clips so that when the coil spins, it just clears the magnets. Adjust the coil and the clips until the coil stays balanced and centered while spinning freely on the clips. Good balance is important in getting the motor to operate well.

Once you have determined how long the projecting ends of the coil must be to rest in the paper-clip cradles, you may trim off any excess wire.

Attach one of the clip cables to each paper clip just above the rubber bands. You may need to readjust the clips to make sure the coil still spins freely.

Hold the other ends of the clip leads against the two poles of the D-cell battery. If the coil is well balanced on the clips, it will rotate to a near horizontal position. The magnetic field created by the electric current in the coil aligns itself with the magnets.

The coil may not continue to turn, because the current continues to flow through the coil its magnetic fields stays aligned with the magnets. To get the coil to continue rotating, the current should be turned off when the coil is aligned with the magnets. This can be done by coating part of one of the bare wire ends of the coil.

Remove the coil from the paper clips. Hold the coil vertically. Use the permanent marker to paint the TOP HALF of one of the two end wires. Allow the ink to dry for a few seconds, and apply a second coat. Allow several second again for the ink to dry, and then hang the coil on the paper clips again.

Connect the D-cell battery again, and give the coil a gentle spin. If it doesn't keep spinning on its own, check to make sure that the coil assembly is well balanced when spinning, that the projecting end has been painted with black pen as noted, and that the coil and the magnet are close to each other but do not hit each other. You might also try adjusting the distance separating the cradles: This may affect the quality of the contact between the coil and the cradles. With a little adjustment, your motor will spin rapidly when connected to the battery. (A holder for the battery will allow you to make the connections without holding them in place.)http://scifun.chem.wisc.edu/homeexpts/BuildAMotor.htm

Pure water does not conduct electricity very well. However, when certain substances are dissolved in water, the solution does conduct electricity. You can make a simple device that shows how well a solution conducts electricity. This device uses a flashlight bulb to indicate how well the solution conducts electricity. The better the solution conducts electricity, the brighter the bulb will glow.

Conductivity Tester

To construct the conductivity tester you will need:

● a 12-volt AC adapter This converts the 110-volt electricity from a wall socket to safer 12-volts. It must be 12 volts AC, not DC, because DC will not work for this. You may have a suitable adapter around the house from an old device you're no longer using, or you may get one from an electronics store (e.g. Radio Shack, catalog number 273-1631).

● an audio cable with a 1/4-inch or 1/8-inch monaural plug on one end The plug will become the probe for testing conductivity. You may have an unused cable around the house. What is on the other end does not matter because it will be removed. You may also get a suitable plug-and-cable assembly from an electronics supply store (e.g., Radio Shack, catalog number 42-2381).

● a 12-volt flashlight bulb and socket The bulb will provide a visible indication of how well a material conducts electricity. You can get these from an electronics store (e.g., Radio Shack, catalog numbers 272-1143 for the bulb and 272-357 for the socket).

● a block of wood about 4 by 4 by 1 inch The electrical connections will be made on this block, and the lamp will be mounted on it, too.

● two 1-inch wood screws These hold the lamp socket to the block of wood.

● one 3/4-inch round-headed screw and washer These will be used to make an electrical connection.

● wire cutter and wire stripper These are used to prepare the electrical connections.

● a screw driver

Cut the plug from the end of the cord of the AC adapter. Separate about four inches of the cord into its two conductors. Remove about 1 inch of insulation from each of the conductors.

Cut the cord of the audio cable about 2 feet from the plug. Remove about four inches of insulation from the cut end of the cable. This will expose bare stranded wire wrapped around insulation that covers a center wire. Unwrap the stranded wires from the insulation and twist the strands together to make a single bundle. Strip about 1 inch of the inner insulation from the center wire.

Electrical connections

Use wood screws to attach the lamp base (socket) to the block of wood. Put the washer on the round-head screw and screw it into the block next to the lamp base, but do not tighten the screw yet.

Wrap one wire from the AC adapter (it doesn't matter which) around the screw above the washer. Wrap the end of the bundled wire from the audio plug around the same screw. Tighten the screw to fasten the two wires together.

Attach the remaining wire from the AC adapter to one of the terminals of the lamp base. Attach the remaining wire from the audio plug to the other terminal of the lamp base.

Screw the 12-volt flashlight lamp into the lamp base.

To make the connections more secure, you can use a heavy staple to hold each of the two wires to the wooden block.

The conductivity tester is now complete and ready to use. To test that it works properly, plug the AC adapter into an AC outlet. The lamp will not light. Touch the audio plug sideways to a piece of metal, such as a coin. When the two metal conductors of the plug are shorted by the coin, the lamp will glow brightly. The bright glow indicates that current is easily flowing through the piece of metal.

Testing a solution

Put some water into a cup. Insert the end of the audio plug into the water. If you use distilled water, the lamp will not glow. If you use tap water, the lamp may glow dimly, if at all. If it glows, it shows that the tap water conducts electricity only poorly. Add some table salt to the water and stir the mixture. The lamp will glow brightly when the plug is put into the solution, because salt solution conducts electricity very well, almost as well as metal.

You can investigate different materials from around your house to see how well they conduct electricity when mixed with water. Some things to try, in addition to salt, are sugar, baking soda, shampoo, laundry detergent, rubbing alcohol, and antacid tablets. Anything that dissolves in water can be tested. In order to avoid mixing the materials you're testing, be sure to rinse the plug in water and dry it before testing a different substance. Do not put the plug in a solution for more than 10 to 15 seconds, because doing so will cause the plug to corrode rapidly. Keep a record of which substances conduct electricity well, which conduct poorly, and which do not conduct at all.

Sometimes, mixtures of substances conduct differently than the separate substances. As an example, test the conductivity of vinegar. Then test the conductivity of laundry ammonia. Then, pour a little ammonia into the vinegar and test the mixture. You will see a big difference between the separate substances and the mixture!

An electric current is a flow of electrical charge. When a metal conducts electricity, the charge is carried by electrons moving through the metal. Electrons are subatomic particles with a negative electrical charge. When a solution conducts electricity, the charge is carried by ions moving through the solution. Ions are atoms or small groups of atoms that have an electrical charge. Some ions have a negative charge and some have a positive charge.

Pure water contains very few ions, so it does not conduct electricity very well. When table salt is dissolved in water, the solution conducts very well, because the solution contains ions. The ions come from the table salt, whose chemical name is sodium chloride. Sodium chloride contains sodium ions, which have a positive charge, and chloride ions, which have a negative charge. Because sodium chloride is made up of ions, it is called an ionic substance.

Not all substances are made up of ions. Some are mode of uncharged particles called molecules. Sugar is such a substance. When sugar is dissolved in water, the solution does not conduct electricity, because there are no ions in the solution.

Some substances that are made of molecules form solutions that do conduct electricity. Ammonia is such a substance. When ammonia dissolves in water, it reacts with the water and forms a few ions. This is why laundry ammonia, which is a solution of ammonia in water, conducts electricity, but not very well.

Sometimes, when two different solutions are mixed, the substances they contain react with each other and form ions. This is what happens when ammonia and vinegar are mixed. An ammonia solution contains only a few ions, and it conducts electricity only poorly. A vinegar solution also contains only a few ions and conducts only a little electricity. But when these solutions are mixed, the ammonia reacts with the acid in vinegar (acetic acid), and they form a lot of ions. This is why the mixture of ammonia and vinegar conducts electricity very well.

http://scifun.chem.wisc.edu/homeexpts/CondTester/SolutionConductivity.htm

www.sciencebob.com

* An empty soda can

* blown-up balloon

* A head of hair

1. Place the can on its side on a flat smooth surface like a table or a smooth floor.

2. Rub the blown up balloon back and forth through your hair really fast.

3. Now the fun part - Hold the balloon close to the can without actually touching the can. The

can will start to roll towards the balloon without you even touching it!

Try This Too: While you've got the balloon out, tear up part of a tissue into tiny pieces about

1/4 inch (.5 cm) big. Rub the balloon in your hair again and bring it close to the tissue pieces.

They will be attracted to the balloon and then jump away.

This works a lot like our bending water experiment. When you rub the balloon through your

hair, invisible electrons (with a negative charge) build up on the surface of the balloon. This is

called static electricity, which means "non-moving electricity" The electrons have the power

to pull very light objects (with a positive charge) toward them - like the soda can.

The project above is a DEMONSTRATION. To make it a true experiment, you can try to

answer these questions:

1. Does the size of the balloon change the power of the pull?

http://www.sciencebob.com/experiments/staticroll.php

1. Thin wire 2. A long nail = 10p is a good size (10P = 10-penny - 3-inches, the size of the nail *) 3. Two 1.5 volt D-cell batteries, AND/OR a 12-volt lantern battery 4. Wire cutter 5. Masking tape 6. A "knife" switch – you should be able to find this in a hobby shop, electronic supply or a

hardware store. Get a DC (direct current) switch ** 7. Electrical tape 8. Some paper clips

Wrap the wire that has been stripped bare very tightly around the nail - at least 50 times. Cut the wire leaving a few inches of wire at each end.

Tape down the end of the wire from the top of the nail to the negative pole of the battery. Make sure the wire is touching the battery end.

Open the knife switch and connect the wire from the bottom end of the nail to the terminal on the knife switch.

Cut another short piece of wire and tape the wire to the positive pole of the battery.

connect the wire from the battery to other terminals on the knife switch.

Close the circuit by closing the knife switch. When you do that, you create a circuit

of electricity that passes through the wire round around the nail.

Touch the point of the nail to a couple of paper clips and watch what happens.

When the electric current passes through the wire round around the nail, it creates a magnetic field that reaches out in expanding circles. When a wire carrying electricity is twisted into a coil, it is called a solenoid. The magnetic field twists with the coiled wire, causing the magnetic field lines to concentrate inside the coil. This creates a powerful magnetic effect inside the coil called an electromagnet.

The magnetic field inside the coil causes the tiny magnetic fields in the metal of the nail to be aligned in one direction (all the north poles point the same way). These little fields all pointing in the same direction add to the coil and make the magnet strong enough to pick up some objects.

How many paper clips can you pick up by the electromagnet? What would happen if you used two batteries and connected them together (make sure you connect the positive to the negative poles if you're using the two batteries)? Try to see how many paper clips you can pick up. Now, try using the nine-volt battery. (Connect the positive and negative terminals like on the regular batteries.) How many paper clips can you pick up? Is there any relationship between the voltage of the batteries and the number of clips you can pick up?

http://www.energyquest.ca.gov/projects/electromagnet.html

1. Lantern battery - DO NOT USE ANYTHING HIGHER THAN A NINE-VOLT BATTERY 2. Small light bulb/lamp or small motor 3. Wire to connect battery and lamp terminal (bare wire, not plastics or rubber covered) 4. Wire clippers

Cut three pieces of wire.

Connect the wires from the battery terminals to the lamp terminals - lamp or motor will light up or run.

Take third piece of bare wire and drop across the two bare wires leading between the terminals - notice what happens. The lamp or motor should go out or stop.

Take the third wire that was laying across the other two wires. Take the wire clippers and cut one of the wires leading from the battery to one of the lamp terminals. The lamp or motor should also go out or stop.

When the third piece of wire was dropped across the two wires leading to and from

the lamp, the wire created a "short circuit." This doesn't mean the electricity took a shorter course, it just took an easier path. When you cut the wire with the clippers, you created an "open" circuit. If you placed a switch on this wire... you would create the same type of circuit you have with any electric light.

http://www.energyquest.ca.gov/projects/open-short-circuit.html

http://www.stevespanglerscience.com/experiments