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| 28. Static Electricity | Worksheet 28 | Video Link 28 | |
| 29. The Electric Field | Worksheet 29 | Video Link 29 |
I am rather confused about Gaussian shapes. What do they help prove? Is it just that electric charge is even at any point on the sphere?
ReplyDelete-Kevin Meglathery
Gauss was a mad man. Essentially, the e lectricfield acts geometrically equivalent to the charge enclosed. So if you had a ball of charge and wanted to know what the e field was at some point inside the ball you could just encapsulate a smaller shaped ball and it would behave like a smaller ball. #genius but how do you prove that mathematically? #calculus
DeleteWhen the Gold Leaf test is shown (20 minutes through on the second video), the narrator showed the gold leaf encased in a wire box, both with and without a wire top. When it had the wire top on it, the leaf wasn't disturbed: Was that because there was an equal negative and positive force around the box?
ReplyDeleteI would say it's because the stand he was using to "lift" the gold leaf was instead blocked by the metal wiring around it, which as you said is equally positive and negative. I think the wiring, if they showed the color coated red and blue for protons and electrons, would have showed red on the top as the electrons of the stand would negate those of the cage.
DeleteAwesome. Thanks!
DeleteIt was interesting to see how everything is interconnected with one another, such as matter and electricity, going back to Franklin's era. In the first video they use the laws of physics to disprove (or explain) magic. Everything in the universe is bound by the force of electricity, a force we can't see or touch. Friction is a way to transfer charge, such as friction between ice particles in the clouds causing lightning. Are lighten jars an efficient way to hold electricity? I feel like some of it would be lost in the process, or be lost over time.
ReplyDeleteCasey,
DeleteI agree. The best part of the first video was most definitely the comparison and connection made between modern magic and laws of physics concerning electricity. For instance, it was easier to visualize the triboelectric effect with an example "magic trick" using the charged rod and rabbit fur. On the case of the windsor machine, its success is due to the device it uses to store electric charge- the lighten jar. Since the inside and outside of the jar are metals seperated by glass, charging the inside while the outside remained the same would allow for an equal dispersion of charge. The force of charge is held between the glass. Again, this is an efficient way to "hold" electricity, although you may want to think about the lighten jar's purpose is to store the electricity while the windsor machine is being turned rapidly. Like in the School House Rock video we watched in class, if we had a super-strength person turn a wheel with friction all day, it would generate electricity. But since this can't happen, we use fossil fuels and other forms of energy.
- Katie Rha
thanks katie :)!
Delete1st video:I really liked the parts involving metal's involvement in electricity. To see that the side opposing the one that is near the positive charge actually has a positive charge itself is very interesting. Additionally, the Vandergraff machine's use was stimulating because of the way the electrons escaped via apparent lightning bolts to the positively charge object/wand.
ReplyDelete2nd video: The intensity description makes me wonder how bright some of the stars we see really are. For that light to reach as so far away implies that they are extremely bright. It sounded like Gauss was saying that have a charge inside a shape did two things: one was that it made the inner charge essentially zero and the other was that the shape or size of this inner charge did not matter, because the shape surrounding it would have the charge spread throughout anyway. Am I right here?
ReplyDeleteI am not understanding the "lines of force". For the most part, I understood everything else, but this is just not clicking for me. I got that it begins positive and ends negative from the worksheet, but what are they used for or what do they do? (I am not even positive of what I am asking because I am not getting the concept of it all together)
ReplyDeleteI think the lines are simply a way to visualize electric force. By drawing them, we can see how the forces between two charged objects interact.
Delete-Kevin Meglathery
Agreed. I think in the second video they mentioned it being a visual thing, that the lines aren't actually there (and they're used to help us understand charges)
DeleteMary Frances,
Deletehere is a link to an electric field video that really helped me understand the concept behind the "lines of force." I hope this helps!
http://www.youtube.com/watch?v=NvNd-0AYAVg
They are a more useful means of visually representing the vector nature of an electric field. If you need further understanding, I would suggest looking at this site: http://www.physicsclassroom.com/class/estatics/u8l4c.cfm
Delete- Lauren Ziereis
In the first video, i was amazed at how such complex concepts can be derived from something as simple as sliding a magnet through a hoop and noticing a change
ReplyDeleteIn the 1st video, I liked how it explained static electricity with pictures. My favorite parts were the gold leaf electroscope and charging by induction. The second video helped me understand faraday cages, gauss's law and electric fields in conductors.
ReplyDeleteThese videos helped me a lot in understanding the concept of the force lines and how they represent the electric field surrounding a charge. I found it very interesting that quarks may be imaginary, I previously took them to be proven to exist. They also really helped me to understand how gauss's law was derived, and just how little we knew about electricity during the time. Its amazing how brave the scientists like Franklin had to be to leap into basically the unknown. I find it remarkable how small things like the kite experiment can alter the course of history in such monumental ways.
ReplyDelete-Jason Rodman
These videos helped me to better understand electric field lines and how they work as well. I can now picture how they would truly look with the 3D images in mind. I also found it very interesting that scientists could have thought of experiments and explanations to test their theories on subjects that were so unknown at the time, especially when they did not have much education, like Faraday.
DeleteJaz Popa
These videos just gave great visual representations all together. The images given for electric field lines and the way multiple charges interact with one another helped me fully grasped how the electric fields would appear. - Jaz Popa
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteIn the first video the visual and description of why metals are conductors, with the sea of electrons and their fluidity, was something that i hadn't really understood prior to this and helped me a lot actually. Is this also how magnets work???
ReplyDeleteAlso, the charging by induction is something that the chapter covered, but was explained very well and helped me explain still a little confused though: i understand that the negative charges are kept in place so to speak by the attraction of the positively charged object near the metal, but why does grounding the metal remove the positive charge from it?
The second video isn't working for me, anybody care to give me a summary or offer a fix?? Sorry! After about 5 minutes it says i have a streaming error although my internet connection is pretty okay.
Yo Marty,
DeleteIn regards to your grounding question. Grounding is simply removing the of the excess charge on an object by the sharing of electrons between it and another object. Typically, an electroscope would be negatively charged, meaning that is has an excess of atoms. To remove the electric charge the electroscope must be connected through a conductive pathway to another object capable of receiving the charge (electrons), being the ground or person. The hand, being a conductor, accepts the electrons and they spread throughout the body. If the electroscope is positively charged the process is the opposite, in that it receives electrons from the ground to balance out the charge. This works because excess positive charge on the electroscope attracts electrons from the ground (or person). This technically disrupts the charge within the person, however, the larger size allows for the excess charge to distance itself.
Thanks Colin!
DeleteYour response, along with today's lesson, helped my understand quite a bit.
Faraday was quite the genius; creating an electric motor with an image of an electric field in his head. Doing so with little to no math. Reminds me of Mr.Crane.
ReplyDeleteor me....
DeleteKind of confused how the Vaan de Graff accelerator works? Also the videos were helpful by showing animations and then a real life example shown but the narrators monotone voice is making me yawn.
ReplyDeleteInside the column that supports the metal sphere is a belt. When it's turned on, the belt starts spinning and rubs against something in the base (I'm not exactly sure what). This friction creates a net charge on the belt and it is transferred to the sphere. When too much charge collects on the sphere, it will try to ground itself, via the air or a finger.
Delete-Kevin Meglathery
Haley, the Van de Graaff accelerator is described as a "constant current" since when you put a load on it, the current remains the same. As Kevin mentioned, when you approach the spear with a grounded object, the voltage with decrease, but the current will remain the same. In regards to how it physically works: the motor is turned on so the lower roller will turn the belt (lower roller has neg charge, belt has pos charge). Since the belt is normally made out of rubber and the lower roller is covered in silicon tape, we can take note in the triboelectric effect
Delete-Lauren Ziereis
The visualizations in the videos made the concepts much easier to understand. The spheres that built up around each other to demonstrate electric flux and electric force helped explain the direction it works in, and how it actually works. The one thing that sparked my interest though was in the first video, it said that lightning was generated through friction of ice particles in the clouds, is that how it actually works, or is there something more to it than just friction?
ReplyDeleteIn the first video, I really liked the comparison between magic and electricity. It made it more interesting and easier to understand, such as the examples of the wand on the rabbit fur and the gold leaf. I also thought that the diagrams like the one on Coulombs Law helped me to understand the concepts better. The narration in the video didn't really do all that much to help me, but the animations gave me a way to visualize an otherwise confusing concept. I think being able to see how something works makes it easier for me to understand. In the second video, I liked the animations of the electric field as well. How to draw an electric field makes a lot more sense now, but I am kind of confused as to how an electric field can exist almost anywhere. Also, the video helped a little bit, but Gauss's Law still confuses me. For some reason I can't grasp that concept completely. Would anyone be able to explain it in simpler terms?
ReplyDeleteThis video helped me understand Gauss's Law further:
Deletehttp://www.youtube.com/watch?v=QNIJC1emss8
-Lauren Ziereis
The videos gave me a solid grasp about electric fields and forces with nice visualizations making it easier for me to learn. I now have a better understanding about electric field lines and how metals play a role when conducting electricity. I'm still left with questions like Gauss's Law and how friction transfers charges when watching the part about lightning. In general the videos showed me how small concepts can be formed into complex ideas and how electrical force always exists in the universe and is used for work.
ReplyDelete-Prem Patel