Thursday, April 28, 2011
TEST IT
Spin the magnet REALLY fast and the bulb will light dimly. If it doesn't work, try spinning it in a dark room so you don't miss the dim glow. If needed, adjust the position of the magnets so they don't hit or scrape the cardboard. This thing has to spin *fast*, and if the magnets whack the cardboard and slow down, you won't see any light. Spin it faster than eight revs per second. (IF IT DOESN'T WORK, SEE "DEBUGGING")
Once you get it to work, try clamping the point of the nail into the chuck of a hand-crank drill. Spin the magnets fast with the drill and the bulb will light brightly. Don't go too fast or you'll burn out the bulb, or maybe fling magnets all over the room. You can try this with an electric drill as well, although electric drills don't spin as fast.
Note: your generator produces Alternating Current, not Direct Current. The output voltage is about 2 volts max, so there is no electric shock hazard at all.
HOW IT WORKS
All metals contain a movable substance called "electric charge". Even uncharged wires are full of charge! After all, the atoms of the metal are made half of positively-charged protons, and half of negative electrons. Metals are special because their electrons don't stay connected to the metal atoms, instead they constantly fly around inside the metal and form a type of electric "liquid" inside the wires. All wires are full of electric fluid. Modern scientists call this liquid by the name "electron sea" or "electron gas," or the "sea of charge." The fluid charge is movable, and this lets metals be electric conductors. The movable charge-stuff is not invisible, it actually gives metals their silvery shine. The electron gas is like a silvery fluid. Sort of.
Whenever a circle of wire surrounds a magnetic field, and if the magnetic field then changes, a circular "pressure" called Voltage appears. The faster the magnetic field changes, the larger the voltage becomes. This circular voltage trys to force the movable charges inside the wire to rotate around the circle. In other words, moving magnets cause changing magnetic fields which try to create electric currents in closed circles of wire. A moving magnet causes a pumping action. If the circuit is not complete, if there is a break, then the pumping force will cause no charge flow. Instead, a voltage difference will appear at the ends of the wir es. But if the circuit is "complete" or "closed", then the magnet's pumping action can force the electrons of the coil to begin flowing. A moving magnet can create an electric current in a closed circuit. The effect is called Electromagnetic Induction. This is a basic law of physics, and it is used by all coil/magnet electric generators.
Generators don't have just one circle of wire. Suppose that many metal circles surround the moving magnet. Suppose that all the circles are connected in series to form a coil. The small voltage from each circle will add together to give much larger voltage. A coil with 100 turns will have a hundred times more voltage than a one-turn coil.
Now for the light bulb. If we connect the ends of the coil together, then whenever the magnet moves, the metal's charges will move and a large electric current will appear in the coil. What if we instead connect a light bulb between the ends of the coil? A light bulb is really just a piece of wire. The charges of the light bulb's filament will be pushed along. When the charges within the copper wire pass into the thin light bulb filament, their speed greatly increases. When the charges leave the filament and move back into the larger copper wire, they slow down again. Inside the narrow filament, the fast-moving charges heat the metal by a sort of electrical "friction". The metal filament gets so hot that it glows. The moving charges also heat the wires of the generator a bit, but since the generator wires are so much thicker, almost all of the heating takes place in the light bulb filament.
So, just connect a light bulb to a coil of wire, place a short powerful magnet in the coil, then spin the magnet fast. The faster you spin the magnet, the higher the voltage pump-force becomes, and the brighter the light bulb lights up. The more powerful your magnet, the higher the voltage and the brighter the bulb. And the more circles of wire in your coil, the higher the voltage and the brighter the bulb.
Spin the magnet REALLY fast and the bulb will light dimly. If it doesn't work, try spinning it in a dark room so you don't miss the dim glow. If needed, adjust the position of the magnets so they don't hit or scrape the cardboard. This thing has to spin *fast*, and if the magnets whack the cardboard and slow down, you won't see any light. Spin it faster than eight revs per second. (IF IT DOESN'T WORK, SEE "DEBUGGING")
Once you get it to work, try clamping the point of the nail into the chuck of a hand-crank drill. Spin the magnets fast with the drill and the bulb will light brightly. Don't go too fast or you'll burn out the bulb, or maybe fling magnets all over the room. You can try this with an electric drill as well, although electric drills don't spin as fast.
Note: your generator produces Alternating Current, not Direct Current. The output voltage is about 2 volts max, so there is no electric shock hazard at all.
HOW IT WORKS
All metals contain a movable substance called "electric charge". Even uncharged wires are full of charge! After all, the atoms of the metal are made half of positively-charged protons, and half of negative electrons. Metals are special because their electrons don't stay connected to the metal atoms, instead they constantly fly around inside the metal and form a type of electric "liquid" inside the wires. All wires are full of electric fluid. Modern scientists call this liquid by the name "electron sea" or "electron gas," or the "sea of charge." The fluid charge is movable, and this lets metals be electric conductors. The movable charge-stuff is not invisible, it actually gives metals their silvery shine. The electron gas is like a silvery fluid. Sort of.
Whenever a circle of wire surrounds a magnetic field, and if the magnetic field then changes, a circular "pressure" called Voltage appears. The faster the magnetic field changes, the larger the voltage becomes. This circular voltage trys to force the movable charges inside the wire to rotate around the circle. In other words, moving magnets cause changing magnetic fields which try to create electric currents in closed circles of wire. A moving magnet causes a pumping action. If the circuit is not complete, if there is a break, then the pumping force will cause no charge flow. Instead, a voltage difference will appear at the ends of the wir es. But if the circuit is "complete" or "closed", then the magnet's pumping action can force the electrons of the coil to begin flowing. A moving magnet can create an electric current in a closed circuit. The effect is called Electromagnetic Induction. This is a basic law of physics, and it is used by all coil/magnet electric generators.
Generators don't have just one circle of wire. Suppose that many metal circles surround the moving magnet. Suppose that all the circles are connected in series to form a coil. The small voltage from each circle will add together to give much larger voltage. A coil with 100 turns will have a hundred times more voltage than a one-turn coil.
Now for the light bulb. If we connect the ends of the coil together, then whenever the magnet moves, the metal's charges will move and a large electric current will appear in the coil. What if we instead connect a light bulb between the ends of the coil? A light bulb is really just a piece of wire. The charges of the light bulb's filament will be pushed along. When the charges within the copper wire pass into the thin light bulb filament, their speed greatly increases. When the charges leave the filament and move back into the larger copper wire, they slow down again. Inside the narrow filament, the fast-moving charges heat the metal by a sort of electrical "friction". The metal filament gets so hot that it glows. The moving charges also heat the wires of the generator a bit, but since the generator wires are so much thicker, almost all of the heating takes place in the light bulb filament.
So, just connect a light bulb to a coil of wire, place a short powerful magnet in the coil, then spin the magnet fast. The faster you spin the magnet, the higher the voltage pump-force becomes, and the brighter the light bulb lights up. The more powerful your magnet, the higher the voltage and the brighter the bulb. And the more circles of wire in your coil, the higher the voltage and the brighter the bulb.
Thursday, April 7, 2011
dynamo
drawing of generator
NEXT PAGE->
CONSTRUCTION
First make the hollow-ended box. Score the cardboard strip like so:
___________________________________________________________________
| 8cm | 3.5cm | 8cm | 3.2cm | 7.7cm |
| | | | | |
| | | | | |
| | | | | |
|8 | | | | |
|cm | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
|________________|________|_________________|_______|_______________|
NOTE: this page must be displayed in COURIER FONT, otherwise
these pictures will be wrecked and unreadable. Most browsers
do this automatically.
_____8_________
_|______________ \
|\ 7.7 | \ 3.5
| \3.2 | \
| \_____________|___\
| | 8 |
| | |
| | |
| | | Fold it like this and tape
| | | it securely.
| | |
| | |
| | |
| | |
\ | |
\|__________________|
________________
_|_______________ \
|\ | \
| \ | \ Use the nail to poke a hole
| \______________|___\ perfectly straight through the
| | | center of the box, going through
| | \ / | both sides and all three layers
| | \ / | of cardboard. Then pull the nail
| | \ (hole) | out and use it to widen all the
| | \ / | holes slightly, so when you put
| | O | the nail back through, it will
| | / \ | be a bit loose and able to spin.
| | / \ |
| | / \ | ( You can find the exact center
\ | / \ | by drawing an "X" to the corners
\|___________________| using a ruler. )
At this point you should clamp your four magnets around the nail and give it a spin. This makes sure the box is large enough. The nail and magnets should spin freely. The corners of the magnets should NOT bump the inside of the box as they spin. If the box is a bit too small, start over and make it a little bigger. Either that, or try a thinner nail. (Also, be sure to use the right magnets. Small ones won't work.)
[YES, you can build a plexiglas box instead if you wish. However, don't make it any larger than this. The wire must stay very close to the spinning magnets, so keep the box as small as possible. It should be slightly more than 3 in. wide and slightly more than 1 in. thick.]
Pick the spool of number-30 magnet wire from
_______________ the kit of spools. This is the thinnest.
_|______________ \ Tape one end of the number-30 magnet wire
|\ | \ to the side of the box, then wind all of
| \ | \ the wire onto the box as shown. It's OK
| \_____________|___\ to cover up the nail hole. Pull the taped
| | | end of the wire out, then tape down both
\ | | of the wires so the coil doesn't unwind.
\\ | | You should have about 10cm of wire left
\\\====================| sticking out.
\\\====================/___
|\\====================/ \
-----+-\====================/ \
/ | ==================== \
/ | | | \ Use sandpaper or the edge of a
| \ | | | knife to scrape the thin plastic
| \|__________________| | coating off 2cm of the wire ends.
| Remove every bit of red coating,
so the wire ends are coppery.
(note: the five lines of wire shown above are not real, that's
the 'equals signs' I used to draw with. The real wire can just
be wound up in a big wad in the center of the cardboard box.)
_______________
_|______________ \
|\ | \
| \ | \
| \_____________|___\ Spread the wire away from the
| | | nail hole and tape it in place.
\ | | Stick the nail back through the
\\ | | holes and make sure it can spin.
\\\====================| Take your four magnets, stick
\\\========---=========/___ them face to face in two pairs,
|\\========(\\)========/ \ Then stick the two pairs inside
-----+-\==========(_)=======/ \ the box and on either side of the
/ | ==================== | nail so they grab the nail. Push
/ | | | | them around until they are some-
\ | | | what balanced and even, then spin
\|__________________| | the nail and see if they turn
freely. If you wish, you can
stick 2cm squares of cardboard
between the magnets to straighten
them, and tape the magnets so they
don't move around on the nail.
_____ magnets
|_____| _____________
|_____| |_____________| 2 magnets
=================|| NAIL |_____________|
|_____| ______O______
|_____| |_____________| 2 magnets
|_____________|
SIDE VIEW OF THE
NAIL AND MAGNETS VIEW FROM THE END
TWIST THE WIRES TOGETHER
Make sure that each end of the generator's wires are totally cleared of red plastic coating. If there is a bit of plastic left, it can act as an insulator which turns off your light bulb circuit.
Twist the scraped end of each generator wire securely around the silver tip of each wire from the small light bulb. (If necessary, use a knife to strip more plastic from the ends of the light bulb wires.) One generator wire goes to one light bulb wire, the other generator wire goes to the other light bulb wire, and the two twisted wire connections should not touch together. In the twisted wires, metal must touch metal with no plastic in between.
_______________
_|______________ \
|\ | \
| \ | \
| \_____________|___\
| | |
\ | |
\\ | |
\\\====================|
\\\========---=========/___
|\\========(\\)========/ \
-----+-\==========(_)=======/ \
/ | ==================== |
| | | | |
| \ | | |
| \|__________________| |
| |
\ /
\ twist /
\ {} twist {} /
\ {} {} /
\____/\______ _______/\__/
\_/
( )
( ) tiny
(_) light bulb
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