slingshot
Posts: 4
Joined: Sat Jan 17, 2004 5:32 pm

HELP! ELECTROMAGNETISM PROJECT HAS FAILED--NEED ADVICE

Postby slingshot » Sat Jan 17, 2004 5:49 pm

My son's project has failed! It was in the book 100 First Prize Make It Yourself Science Fair Projects by Glen Vecchione. His project was called "A Springing Spring". The steps are as follows: 1. Twist a thin copper wire around a pencil to make a coil. 2. Put a thick copper wire piece though a small styrofoam balll. Put a pencil into the side of the cork. 3. Tape the other end of the pencil to the side of a book. Place this book on top of a pile of books so that the pencil, styrofoam ball, and wire hang out from the stack of books by about 5 inches. 4. Stretch out the coil of copper wire so that it becomes a kind of string. Straighten out each end of the spring and twist one of the ends around the thick copper wire sticking out from the bottom of the styrofoam ball. 5. Strip the plactic insulation from the ends of two pieces of insulated wire. Attach each piece of wire to a terminal of a 6-volt battery. 6. Attach the opposite end of one of the wires to the thick copper wire sticking out from the top of the styrofoam ball. 7. Fill a small bowl with warm water and add salt until no more salt dissolves. Place the end of the copper spring in the saltwater so that the wire sits just below the water's surface. 8. Take the disconnected piece of insulated wire from the battery, and gently dip the stripped end into the saltwater. The results are that when the battery connected wire touches the saltwater, the copper spring is suppose to bounce wildly. However, it doesn't. Any suggestions??????? Thanks for your help!

kenzad01
Posts: 7
Joined: Sun Jan 18, 2004 10:09 pm

Postby kenzad01 » Sun Jan 18, 2004 10:39 pm

You may have a poor or no connection. some wire has varnish on it. If you don't have an ohmeter to test continuity of your connections, another way is to use a battery and a light bulb with the wires--etc. Use something to finely scratch the surface of all wires connected to assure a good connection. Sandpaper or emery works, but be sure to wipe off after because they deposit insulating sand or abrasive onto the wire.
Kenneth A. Zadwick

slingshot
Posts: 4
Joined: Sat Jan 17, 2004 5:32 pm

Postby slingshot » Tue Jan 20, 2004 7:12 am

Thank you for your reply, however we have already done all the suggestions that you made. Should this project have worked??????

kenzad01
Posts: 7
Joined: Sun Jan 18, 2004 10:09 pm

Postby kenzad01 » Tue Jan 20, 2004 8:33 am

OK, There is some info left out in your data posted.
The idea here is the coil creates a progressive magnet as current flows thru it. The one point I am not sure of you apparatus:
The part about stretching out the coil. To work, we need to have many turns of wire, and each turn should not touch the next one. The salt water is to act as a resistor, since a direct connection to the wire would cause great heat and run the battery down quick- too much current. Your are trying to create a pulse of current into the coil. the coil may be stretched out so the coil part is not close wound. So, I wonder how many close wound turns do you have left when you are ready to make the final connection?

Back to the pulse idea: When you connect the wire to the salt to make the current flow thru the coil, it flows rather slow to build up a magnetic field.
When you pull the wire out of the salt the magnetic lines of force drop extremely fast , since there is no circuit resistance-- only if you pull the wire quickly and completely out of the salt water. One such action for each contact. Seems to me, to make it dance you would need to keep touching, and pulling out the wire quickly.=== not disturbing the coil mechanically.

KZ

The coil should be hanging freely so no tension resists it's movement.

Another poss. is the salt water isn.t conducting, or the battery is old, and cannot generate the short pulse of high current needed to make this work.

A battery can show full voltage, but not able to keep up with the current needed. You should have an volt ohmmeter. One test is to connect the voltmeter across the battery, and watch to see if the voltage changes when you complete the circuit. Another is to see if the salt water is conducting. Use the battery and wires to make a circuit with the spaing in the salt water you are using. The farther away in the water the leads your are using, the lower the current to the coil. Maybe you can't get enough current flowing thru the salt because of too much resistance between the two point in the water--?? Or just try to use the wires contacting the water closer together, not shorted.
Kenneth A. Zadwick

slingshot
Posts: 4
Joined: Sat Jan 17, 2004 5:32 pm

Postby slingshot » Sat Jan 24, 2004 7:45 am

Thank you again for your suggestions.

We have tried two different coils of wire. One where they are closely wound together, but not touching. The coil has 35 turns of coils wound. The other was not as closely wound together, again not touching. It had 21 turns of coils wound. For this we are using one strand of wire out of a 14 gauge electrical wire.

The other wire that we put thru the styrofoam ball is 14 gauge wire.

We even tried a second 6 volt battery. We checked the voltage on both batteries and they are okay. We then hooked up the two batteries to make 12 volts. We used a light bulb with this experiment and it worked. However it still doesn't make the spring move.

The coil is hanging freely.

We tried touching and pulling the wire our quickly. All it did was bubble a little.

Do you have any other suggestions?

HScienceGuy
Posts: 2
Joined: Mon Dec 15, 2003 9:14 pm

Postby HScienceGuy » Sat Jan 24, 2004 4:24 pm

Unfortunately, there are quite a lot of variability in this experiment. You'll need to fiddle with the length of wire, tightness of coil, solution salinity, and copper connections.

kenzad01
Posts: 7
Joined: Sun Jan 18, 2004 10:09 pm

Postby kenzad01 » Sun Jan 25, 2004 2:03 pm

I have researched a lot of places on this item. The coil did not noticeably move in one case tried by others.

Where it works is as I said before, lots of current. The demos similar use a car battery to get enough current. In fact they warn about only 3 secs to avoid melting the wire. A version which might work at lower currents is to put a strong refrig. magnet nearby the coil. The magnet field created will cause a non magnetic coil of copper to moveas it react with the field of the permanent magnet. In this case it is the energized state that forms the magnetic field.

KZ
Kenneth A. Zadwick


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