Using a Van de Graaff generator
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- čas přidán 7. 02. 2019
- From the Institute of Physics and the National STEM Learning Centre and Network (www.stem.org.uk/), this video is aimed at teachers and shows how to get the best out of a Van de Graaff generator. In the video, Michael de Podesta explains how the generator works and gives some tips on getting consistently good results when using the apparatus. The video concludes with a simple but effective demonstration of charge.
- Věda a technologie
thank you for the explaination
This is a nice demo and a rather-complete explanation, but I think there are several misleading statements, per what I have learned from various electrostatics experts.
At 2:58 minutes, the charge transfer is not caused by friction but rather by mere contact of the dissimilar materials. However, mere touching only brings the high points of the surfaces into contact. The motion does help considerably by producing a lot more points of contact.
At 3:49, if the rollers are made of the same material, I think the generator can still work (but not as well) because of the mutual repulsion between the electrons. The electrons "want" to go to the outer surface of the sphere to get as far apart as possible.
At 4:15, moisture in the air does not enhance the conductivity of the air, but the moisture does enhance the conductivity of many materials that are exposed to the moist air, as was pointed out.
At 6:38, only the top surface of the top tin and the outer surfaces of the outer rings of the other tins become negatively charged because of the mutual repulsion of the electrons. Once the top tin flies off, charge rushes to the top surface the next tin causing it to fly off, and so on.
At 6:43, the weight of the top tin is not the primary reason the others don't immediately begin to fly off. Rather, the others do not experience significant repulsion because they are not yet charged except at their outer edges. This can be demonstrated by using a stack of thin aluminum foil disks rather than the heavier cups. The thin foil disks also fly off one at a time in sequence just like the cups do, and the lower foils show no tendency to rise until they become exposed. However, if two such foils are taped together, they fly off just fine, showing that the electrostatic force is considerably stronger than the force of gravity on the two disks together.
I wish my Physics class was like this :D
So, its more of an electron pump? I remember these back in the days in science class. I want to build one. Electricity is awesome. Dangerous but awesome.
Sir i have a question
1) why we take a sphere for the domb why not a square a rod
2) what if the same experiment is performed in vacuum
3) will the spark show change if we bring a magnet towards it .
It is possible to obtain the sparkle electricity to charge a battery?
Hello Mr. Podesta,
Thank you for the explanation.
But I have few questions.
- Is this possible, that all the hairs head after than the Ball touched would, standing position.
- And the next question, how long time is necessary?
- Is that dangerous for he, that after standing his hair, I spray " hair spray " of his hair.
3:29 if the upper roller attacts electrons less strongly than the lower roller, why do the electrons get transferred to the upper part?
What happens if you put a UV Lamp facing the side of the belt that's has an accumulation of electrons?
.... Do you get X-Rays or even Gamma Rays??
"Then it's time to get a new belt..."😅
Just run down to the local hardware store
Actually, electrons do not directly move from the combs to and from the belt. The charges are carried by charged ions (air molecules) moving to and fro from the belt to the combs. That kind of Van de Graaff generator will not work in a vacuum!
Ghost hunters sent me here
It probably works like a Tesla coil.
No