| Author | Message | ||
     Anonymous |
If you have two wires wound together around an iron core and electricity passed through one of the wires would electricity passing through the other wire have more resistance when flowing the direction opposite to the first coil than with it? | ||
| Simon Quellen Field (Sfield) |
You might not be able to measure the difference, but the resistance will increase slightly. Any time you have a current flowing in a wire, and you place the wire in a magnetic field, you will see the resistance rise. This is because the electrons are pushed to one side of the wire by the magnetic field. The electrons are no longer using the entire cross-sectional area of the wire, so the wire behaves as if it were thinner. But at accessible magnetic field strengths, it may be difficult to measure this small effect. | ||
| Anonymous |
What I'm trying to do is see if I can use magnetism to help charge up a capacitor more than its normal capacity would let it be charged. Right now I'm thinking that if I have two coils wound together, the coils are only attached at one end so they act like the capacitors plates normally would. As a small amount of current flows to charge up the capacitor, it should also establish a magnetic field, the field will collapse inducing current in the wire and overcharging the capacitor. I'm going to build this with a detachable iron core (should help the magnetic field right?) and I will measure the capacity with and without it, but I'm not sure how to measure the capacity, do I just charge it up and measure it like I would a DC battery with my multimeter? | ||
| Simon Quellen Field (Sfield) |
There are two measurements important in a capacitor. One is the voltage it can be charged with before the dielectric breaks down, and the other is the amount of charge it can store. The voltage is a function of the insulating properties of the material between the plates, and the distance between the plates. The farther away the plates are, the higher the voltage can be before the insulator is breached. The charge is a function of the area of the plates, and the distance between them. The larger the plates, and the closer together the plates are, the more charge you can store. A third factor is the internal resistance of the capacitor. The lower the resistance, the faster the charge can be delivered to the load, and thus the higher the current. The energy delivered to the load is the product of the voltage and the current. If the voltage is as high as the insulator can withstand, and the charge is delivered to the load with the least resistance possible, then the amount of energy delivered to the load will be maximized. If you have two plates close together, and charged with opposite charges, they will attract one another. If you do work against this attraction by pulling the plates apart, you are adding energy to the capacitor. You can get this energy back when you dump it into the load. One way to measure the energy stored in a capacitor is to dump the energy into a load, and measure the output. The load can be a heating coil in a water bath, and you can use a thermometer to measure the change in temperature of the water. A capacitor works by taking electrons from one plate and pushing them onto the other plate. This gets harder to do as more electrons are moved. The force that moves the electrons is the voltage. As the capacitor charges up, the voltage rises in the capacitor, until it approaches the voltage being applied to the capacitor from the outside. As the difference in voltage decreases, the speed at which electrons are moved from one plate to the other decreases, until the voltages are matched, and no more electrons flow. If the voltage tolerance of the insulator is exceeded, electrons will jump across it from one plate to the other, and energy will be lost. It is not clear from your description whether you expect to be able to increase the voltage without breaking doen the insulator, or to increase the area of the plates, or to move the plates farther apart. I can see no reason to expect any of those things to happen. | ||
| Anonymous |
I have a device that is two open ended coils that are open ended so they act like the plates of the capacitor, but its a coil so its also an inductor and I'm hoping that the magnetic field established will charge it more when it collapses. The effect might be something like putting an inductor in series with the capacitor so you have the setup (power source) -> (inductor) -> (capacitor) -> (back to the power source). Depending on how large the capacitor is there should be a small flow of current to charge it up, establishing a magnetic field in the inductor which will induce more current when it collapses and overcharge the capacitor. I expect it may be like putting more voltage into the capacitor than is supplied by the power source but I’m not sure. | ||
| Simon Quellen Field (Sfield) |
You can probably do the 'experiment' digitally, using PSpice instead of actually hooking up hardware. Do a Google search for PSpice. | ||
| mnado (Mnado) Senior Member Username: Mnado Post Number: 192 Registered: 12-2005 |
What kind of metal is found inside a capacitor? I think i can used that in the fuel cell. |
