Electrostatic machine - a static charge generator, which consists of two wheels rotating in opposite directions. It is often used by teachers in physics classes for intimidation electric arc engaged by force.
Design
The design of the invention is described by James Vimhersta bad in the public domain, people often can not explain how the electrostatic machine.
general idea
Two rotating against each other coaxial drive are simple capacitors from aluminum sectors. Due to stochastic processes at the initial time in one of the segments - are uniformly arranged in a circle - the charge is formed. This is caused by the friction of the process air or other reasons. Moreover, since the symmetrical design, the sign is not predictable in advance. It is not recommended to put in the electrostatic machine electrolytic capacitors.
Instead, two Leyden jars are used. Their external lining foil combined to create a single system of series-connected capacitors. So reduced requirements for the operating voltage of each tank twice. Denominations are selected as similar as possible. Otherwise, the requirements for the operating voltage are distributed unevenly, which leads to negative consequences.
The voltage from the drive segment is removed by means of induction converters. The following describes the principle of operation. In fact the design, which resembles a metal comb, at a certain height above the disk floats. Neutralizers paired in pickup point charge both disks come with an equivalent sign on the outer surface. After unloading the charge segments decreases strongly. This is due to a special design of induction neutralizers, leaving the surface charge density in the region of 0.2 - 6 SCLC per meter squared. The selected designs brush lightly touches the edge of the disk.
Progressive growth of the surface charge density at the point segments detachably caused by that meet moving the system to each other, creating electrical field whose intensity directed in opposite side. It turns out that the operator's own hand (either by the force of the electric drive) system repulsive force brings. Interacting charges are trying to stay away from each other. This causes a sharp increase in the surface charge density at the points of pickup.
From combs converters electricity going in the Leyden jar. Tension is growing rapidly, to avoid system failure due to exceeding the permissible parameters of capacitors, two electrodes attached to the arrester. The distance between them, tend to be regulated to provide an arc of varying strength. The greater field strength between the spark gaps, the effect is accompanied by a noisy process Leyden emptying cans.
After charge removal point segments remain empty. 30 degrees during the movement of the disc are the potential equalizer, called converters on the principle of action. The review authors would have called levelers. Opposite sides of the disc already gave the charge in different brushes. Therefore, after passing the point marks detachably charge residues on them always different. And a thick piece of copper wire with a brush made of thin wires, the grinding segments or hovering at low altitudes, these short-circuited opposite. As a result, the charge on both segments is equal to zero, the energy converted by Joule-Lenz in the heat generated on the thick copper core.
After zeroing discs continue to move in the opposite direction. So, the charge released from one segment of the circle of rotation is opposite to the other half-empty segment. Charge between the containers immediately divided equally, because the drives are designed for the same drawings. Consequently, they appear to be identical. The first disc gives half charge, is on the point of removal. The second potential equalizer reaches a point where the first and giving half charge.
Sometimes people are interested in the principle of operation of the device, since the first drive gave the residual charge on the equalizer, the second to do the same. Where do I get the energy to change the sign?
Explanation of the principle of work
The energy to change the sign in the equalizer taken from the operator's force. Remember, already between the brushes and levelers discs move towards each other with mutual repulsion. The charge density is increased. The principle of operation of the equalizer is not different from a stripper. A stronger charge of the opposite disc literally pushes through the remains of copper wire to be discharged, and power enough for a change of sign.
In the car, the charge removal by increasing the surface density. At one point, energy is stored in the Leyden jar, the other serves to change the sign. And induction converters, apparently, once did not differ from each other. That is why there is confusion with the names. In fact, both - converters. If the trailing wire made of copper with removable brushes called equalization, to pun disappeared. Learn more:
- The design of the two types of capacitors. Firstly, to the specified class includes Leyden jar as battery storage. Secondly, each segment of both disks is considered a capacitor with aluminum plates and a dielectric between them.
- In the car, two types of converters in fact their actions - reducing the charge of aluminum segments. The first serves to charge Leyden jars, the second - for polarization (sign change).
All energy is ultimately not taken from electrification by friction with air, or copper and aluminum, their uncoupling. No! The energy is obtained by the forced filling capacitors force torsion drive. A process executed by a sharp increase of the surface charge density in the pick-up points.
induction converters
Converters in the process can become contaminated. Consequently, the required cleaned periodically, or decreases efficiency. In the car Vimhersta fact reduce efficiency plays little role. If the machine does not work, it is necessary to check the purity of the needles. The design uses four induction converter:
- Dual equalizers are substantially perpendicular to each other.
- According to one stripper - per Leyden jar.
Represent a brush of a thin wire or flat sharp toothed combs (comb). The basis is a metal that is used in the car Vimhersta, and wood. Metal tip always, purpose - as quickly as possible take charge on the ground. Principle of operation: the closer to the tips charged plane line tension interlock them, forming a high value.
For reference. The density of field lines is directly proportional to intensity at that point.
Increased density in the edge region promotes ionization of the air (no sparks) and the formation of charges of both signs, conducting current in the desired direction. neutralizers parameters depend strongly on the distance between the tip and decreasing radius of curvature (sharpening). Applied in the machine Vimhersta wire converters in the form of brushes least effective. On Strippers are comb or needles. It is thought that for maximum effectiveness the last converters is achieved under these conditions:
- Needle height ratio of the distance between them of from 0.6 to 1.8.
- needle length 12 - 50 mm and more.
- Needle diameter 0.5 - 1 mm.
Reducing the sharpening angle of 60 degrees (increase in the curvature) in this case a weak effect on the properties of catalyst. Needles desirable to bring a distance of 5 mm from the surface. The closer, the faster the charge removal. In fact, the minimum distance to the plane depends solely on its own vibration drive. Touch does not lead to a system failure, but fall sharply service life due to mechanical destruction of the individual elements.
In contrast to conventional wisdom, created by endless demonstrations of the machine, the needle is best mounted on the dielectric base. Step taken reduced capacitance between the disc and the ridge than the charge density increases: C = q / U. The charge already specified a priori, lowering capacitance increases the potential difference (voltage) than the ionization process is facilitated.
For safety converter is supplied with the housing. It is worth recalling that the other parts (other than turning the knob) Vimhersta machine during the work can not be touched. The edges of the housing are removed from the neutralizer needle at least 50 mm.
Induction type instrument called for action at a distance. The process is called electrostatic induction. This means that a charged object in the distance affects the second, without charge. In a metal, the electrons are weakly bound to the grating, easy to go in the direction where addicted to the field. The effect is superficial for good reason - the line of tension can not penetrate metal. In another way: the charges in the thickness of the conductor are redistributed until completely neutralized by the external field.
As a result, the needle surface charge is induced. field lines are closed on it simultaneously converge everywhere as shown. potential difference grows immensely is caused air ionization. A review, when the machine Vimhersta on brushes, there is usually no sparking.
instead of a conclusion
Induction converters may be used otherwise - removing the charge from liquid dielectrics. For example, oil. In the production of any spark would cause a negative impact. Just think of the explosion at the well in the Gulf of Mexico.
Thus, the comb is able to slide on the disk. In earlier designs was made uniform without sectors and a dense homogeneous material (see. Fig.). I worked without aluminum capacitors. Physics, a good understanding with the machine, it could be improved.
Thanks
The authors are sincerely grateful to fellow overseas Relatorio Finals for clear and vivid images and photos. Original work is laid out for all to see at the following address: ifi.unicamp.br/~lunazzi/F530_F590_F690_F809_F895/F809/F609_2013_sem1/AlexandreD-Mauro_RF2.pdf.
Without yutubovskih channel store Chip & Dip authors would not have seen the wonderful screenshots: youtube.com/channel/UCUlNxWT1y3SmOmeYzqAKrWQ
