How can an electronic toobruch recharge on its base with no metal contacts??
341660
Induction. \n\nWhen you wind a conductive wire into a coil and pass a current through it, you create a magentic field that extends from the coil.  Similarly, if you hold/move a coiled wire in a magnetic field, you "induce" a current flow in the coil.  With AC, there's no need for the coils to move relative to one another. (That's how a transformer works)  The toothbrush base has a coil in it, and the AC coming out of the wall goes through a coil in the base, induces current in the coil in the toothbrush, and that current charges a cell in the handle.\n\n Here are some neat links:\n\nhttp://www.energyquest.ca.gov/how_it_works/transformer.html\n\nhttp://micro.magnet.fsu.edu/electromag/java/faraday2/
1131106
See if the manufacturer offers a USB cable for the phone (brand would be nice).  Those usually recharge the phone while connected (check manuals)
264255
First of all the physical care. Find an protective carry case, keep it from heat & cold & Water.\nIt is a good idea to let the battery run down the first few times and then recharge. I am told this is good for prolonging the life of the battery.
1175973
You asked several questions.  My answer applies to the generation of "free electrons".\n   If you can, picture the structure of an electronic vacuum tube, the invention of which (the triode, at least) is attributed to Lee Deforest. Thomas Edison worked on  similar devices.\n1) A material (such as Thorium) is electrically heated to a temperature such that electrons are "boiled off" and are electrostatically attracted to a positively (voltage) charged "plate" in a vacuum.  This flow of free electrons is a current (amperes).\n2) These electrons are NOT recycled.  The Thorium gradually deteriorates - is worn out.  \n3)  In a similar manner, this may be a source of electrons in the devices you mention.
342190
If you can get your hands on a solution of silver nitrate, it should be pretty easy.\n\nYou'll need a battery (9 volt should do it) and two lengths of wire.  Run one wire from the positive terminal of the battery and attach it to a silver electrode (available in science shops) or any piece of silver.  If you can't get the silver electrode, just use the copper wire.  This will plate some of the copper onto the ring, though.  Attach the other wire to the ring and to the negative battery terminal.  Lower the ring and the silver electrode into the silver nitrate solution (without letting them touch) and wait.\n\nThe positive silver ions in the solution will be attracted to the negative ring and should plate the ring nicely.
55953
Make a battery from a lemon!\n\nhttp://www.energyquest.ca.gov/projects/lemon.html
425947
You need copper, and any sized battery. Then you need to do some playing around with it. Or you could just go here and do what they tell you.
252510
a battery? i dont know lol or eyes
465838
Well, NiCd and NiMH batteries can be charged and stop charging at full charge without the help of some device to determine if it's full. Once the NiCd and NiMH is full, the current will just pass through and waste your electricity (and if it's left charging at full charge for extended periods, it can also damage the batteries). So it doesn't actually disconnect the current. Just passes through.\n\nBut in Lithium ion batteries, you need some kind of device to determine if it's fully charged. Cellphones, PDA, and iPods kinds of turn on (like, it shows the charging display, but it's not actually on and in your normal thing) when it's plugged into a current so it can detect if it's fully charged. So basically, the device is the mini-computer that determines the charge of the battery.\n\nSo, to answer your question, don't try to create a circuit that will disconnect the current when a Lithium Ion battery becomes fully charged, unless you have the capability, materials, time, and patience to do it. And steady hands. It's really tricky to build a Lithium Ion Battery charger.\n\nPS Penguins!!!
637699
they are working on this, it is a sheet the size of a peice of paper (roughly) but thicker and it uses magnetic induction to recharge batteries without wires
733809
B battery (vacuum tubes)\nFrom Wikipedia, the free encyclopedia\nJump to: navigation, search\nIn electronics, a B battery is any battery used to provide the plate voltage of a vacuum tube. It is sometimes colloquially referred to as a "dry battery" (although there's no reason why a "wet" battery of suitable voltage couldn't be utilised for the purpose) The term comes from the days of valve (tube) radios when it was common practice to use a dry battery for the plate (Anode) voltage and a rechargeable lead/acid "wet" battery for the filament voltage.\n\nEven when the plate voltage rail is fed by a power supply rather than a battery, it is generally referred to as the "B+" line.\n\nhttp://en.wikipedia.org/wiki/B_battery_%28vacuum_tubes%29\n\nAND Check out\nhttp://en.wikipedia.org/wiki/List_of_battery_sizes
175787
you must use some one plug to fill your battery. but make sure your battery can bear the  power of plug.\n\nhahahahahahahahahahaha
219811
!WARNING!\nFirst before I even answer your question.  I just like to warn you that if your actually attempting a stunt like this be very careful.  Connecting 100 AA Batteries(1.25V) in series will produce 125 Volts.  Be very careful with it!\n\nAnswer:\nThe SI units of the electric field are volts per meter.\nThe equation for an electric field is: (E=V/r)\nWhere E=Electric Field, V=Voltage, r=distance from point.\nSo a higher electric field means two things: Higher voltage, or less distance. In order for you to get the highest voltage connect the batteries in series as follows:\n\nConnection: \nYou would need to connect the battery in series as follows to get the highest voltage. \n Bat1  Bat2  Bat3  Bat4  Bat5  Bat6      Bat100\n[- +]o[- +]o[- +]o[- +]o[- +]o[- +]o....[- +]o\n\n\nWhy:\nThe electric field is dependent on the voltage and distance. Increasing voltage will directly increase the electric field.  Decreasing distance will increase the electric field. Look at the equation above. E=V/r\n\nAnother way to think of it:\nThink of Voltage as pressure. And a ball as an point charge(electron).  Suppose you have a water hose and a ball.  You have to use the water hose to move the ball around.  If your too far away from the ball, the water will not reach the ball and the ball won't move.  The same thing happens in electric field.  The electric field is too far from the electron to make it move.  Now suppose you increase the pressure on the water hose.  Because of the increased pressure(Voltage) the water will shoot further and hit the ball, thus moving it.  If your very close to the ball you can use the water pressure(Voltage) to move the ball faster.
323464
Someone has used a gasifier and captive-piston engine to make a one-moving part alternating-current generator. The piston is magnetized and the coils are in the body of the cylinder. The trapped air in the cylinder at each end of the piston acts as an air shock to eliminate rebound and impact damage. No sensors needed. No make and break circuit. The voltage drops to zero at the end-points of travel of the piston. Search on this and you can probably find the same one I saw. I think this is where they got the idea for those new shake-up LED flashlights.
260531
The battery has two terminals, one positive and one negative, with two different types of metals.  Floating inside the battery is also a supply of acid, which scientists would call an electrolyte.  This acid keeps the electrons flowing between the positive and negative terminals all the time.\n\nWhen you set up a wire loop, one end is connected to the positive terminal and the other is connected to the negative terminal.  The free electrons inside the battery like to flow from the positive down to the negative terminal.  Now they have a way out of the battery through the wire.\n\nThe electrons flow through the wire and anything else connected to it, like a small lightbulb.  Some of the electrons are used to make the filament inside the lightbulb glow red hot.  The rest of the electrons continue around the loop and end up at the positive terminal of the battery again.  This process keeps going until either almost all of the electrons are used up in the lightbulb (the battery is 'dead') or the circuit is broken.
25253
You are on the right track. It relies on inductive charging:\n<quote>\nIf you own an electric toothbrush, there's a good chance that it has a completely sealed toothbrush unit. The toothbrush rests on the charger without any metal contacts to connect the toothbrush to the base. This has the great advantage of allowing the toothbrush to be completely sealed so that water cannot enter through exposed contacts. It also avoids any problems with water getting into the contacts and shorting out the charger.\n\nThis sort of sealed arrangement is called inductive charging. Essentially, the toothbrush and the base form a two-part transformer, with the base having one part of the transformer and the toothbrush having the other. When you slide the toothbrush onto the base, the complete transformer is created and charge can flow.\n\nThe base contains one of the coils and the metal bar. The toothbrush contains the second coil. When you drop the toothbrush onto the base, you create the complete transformer!\n</quote>
95055
check with the manufacturer of your phone or a local electronics store like Radio Shack.  Older cell phone batteries used to need to be drained fully in order to preserve their lives, but a lot of new cell phone batteries don't require that anymore.