The Van de Graaff generator was invented at the beginning of the twentieth century. It was used for various purposes, in particular, for nuclear research. Later, the use narrowed. Today you can buy it as a toy and demonstrate to children the levitation of various objects. You can also build a generator yourself. Then it will become an excellent training model with which various experiments are carried out.
Baby tricks
Do you want to create "magic"? Take a plastic bag, cut off both ends and tie with a string to make a bow. Then rub an ordinary plastic ruler well on a woolen thing and bring it to the bow: the flight will begin …
You can also buy a ready-made "magic wand" with figures with which you can do such tricks in the store.
But the easiest way to see the "magic" is just to pet the cat. Then you can both feel and see the resulting static electricity.
And here is a toy that repeats the designVan de Graaff generator, battery operated. When the button is pressed, an electrostatic charge is created at the tip. Therefore, the figurine adopts it, and charges of the same name begin to repel each other. Since the figurine is carved in a certain way, it "inflates" and gets volume. If the charge weakens, then you just need to press the "magic" button again.
A bit of history
Of course, the Van de Graaff generator is not only children's toys. The physicist himself created his brainchild to conduct serious research in the section of atomic physics. The first demonstration sample was made in 1929. It was small in size. More impressive dimensions were obtained by the Van de Graaff generator, mounted on rails for airships. The model consisted of two pillars topped with hollow aluminum spheres fifteen feet in diameter.
The installations built in 1931 and 1933 reached a power of seven million volts. But only a charge of up to eighty kilovolts was provided by the first Van de Graaff generator.
Operation principle
A paper dielectric tape rotates vertically inside. The roller located at the top is a dielectric, and the lower one is made of metal and is connected to the ground. The brush electrode in the sphere removes and supplies the charge, which was distributed evenly in the sphere. Near the electrode below, the air is ionized, useful ions settle on the tape, and the part of it that goes up is charged.
To obtain a high potential difference in linear particle accelerators (which is what these generators were for), two spheres with different charges were used. In one of them accumulated positive, and in the other - negative. When the concentration reached a certain level, an electric discharge jumped between them. It was he who was investigated. The voltage here reached millions of volts.
Previously, devices were used for nuclear research and particle acceleration. After other methods of acceleration appeared, they began to be used much less frequently in this area. Currently, the Van de Graaff generator is mostly used for modeling. For example, with its help, natural gas discharges are imitated. Instead of tapes, installations often use chains consisting of plastic and iron links alternately.
What you need to assemble the device yourself
The model is easy to build yourself from improvised means. The Van de Graaff generator, assembled with his own hands, consists of the following components:
- pencil;
- pvc pipe cutting;
- rubbers;
- staples;
- aluminum foil;
- engine from toys;
- broken bulb;
- dry pastes from the pen;
- 9 volt batteries;
- adhesive tape;
- wires;
- boards.
All elements must be dry, as well as the air in the room. Otherwise, the design simply will not work or will, but veryweakly.
This is how the Van de Graaff generator will turn out. The photo below shows what the model should look like.
How the generator is made by yourself
First, a hole is drilled on the plank, which will become the base of the structure. The drill is selected with a suitable diameter, the shape is in the form of a pen. Then two holes are made on the tube: top and bottom, for pastes. Make two more holes: one just above the top, and the second - perpendicular to the bottom.
Next, the paste must be completely cleaned of ink. Cut out a piece corresponding to the inner diameter of the pipe. They take a paperclip, straighten it and cut a piece long enough so that it protrudes a centimeter from the tube.
Dielectric tape is made from adhesive tape. The gum is glued so that both sides are also sticky.
Prepared items are collected.
Add brushes that collect charge. At the bottom, the brush passes through the hole, and the tip is made fluffy. The brushes should be close to the elastic, but not touching it. The top is threaded through the hole at the top.
After that, with the help of aluminum foil, a light bulb that is already inoperative is pasted over. The top wire is attached to the foil. The lamp is inserted on top of the structure.
Van de Graaff generator training ready.
Experiments
If you attach several threads to the upper electrode and bring your hands closer, they will “stand on end” and wrap around your fingers. Try experimenting in the dark.
To get a more powerful voltage, connect two generators.
A good option for experiments would be a Leyden jar.
The most famous experience is the one in which the hair stands on end. To do this, stand on a rubber mat, wooden board or plywood. The hand is placed on the sphere (while the generator must be turned off so as not to be shocked). When the appliance is turned on, a spark will pass, causing the hair to stand on end.
The generator should be discharged after each use and handle it with extreme care, as the current can be deadly to humans.
