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  1. M

    Current electricity

    You might want to look up Kirchoff's Rule, also. I think you are trying to ask what the ammeter readings will be in that circuit diagram, it can be answered by the said computational method. Intuitively, at the split, the current reading should be lower, this is a direct consequence of the law...
  2. M

    What does it mean to have a negative change in current?

    So, at the negative part of the wave where the slope is negative, is that where the current is increasing and but goes the opposite direction (intuitively, becoming more and more negative)? That means there are different ways to interpret a di/dt or dq/dt that is negative.
  3. M

    What does it mean to have a negative change in current?

    Yes I do of course, it's also the very reason that I'm having conflicting ideas. In the context of calculus (at least from how I knew it), a negative dq/dt would mean that there are decreasing charges as time goes but when the textbook says negative dq/dt also means charges moving in the...
  4. M

    What does it mean to have a negative change in current?

    Does a di/dt<0 mean an increasing current moving from a lower potential to a higher potential (if we define the direction of current to be the flow of the positive charges)? Similar question with negative current i.e.; dq/dt<0.
  5. M

    Electric fields in an Inductor

    @mfb: Does that mean that I just have to believe that proposition? I mean, if it's an experimental fact, then I don't have any problems with it. I'm just a little irked by how it's presented to me I guess, or most probably I've missed something crucial.
  6. M

    Electric fields in an Inductor

    En and Ec are the non-conservative and conservative electric field respectively. I've quoted this from the textbook I'm using (University Physics by Young and Freedman 12th edition). Now, it seems to me that the author just invoked the assumption that the inductor have negligible resistance...
  7. M

    'Rolled' homemade capacitors

    Yes, I have realized this the hard way, one of the reasons I'm playing with the idea of doing theoretical work (I don't know on which field yet). Doing experiments just isn't my thing, at least for now that's how I see it. Thank you Sophiecentaur, you have given me so much insight on this, I'd...
  8. M

    'Rolled' homemade capacitors

    Well, the problem is, what I'd like to do is compute for the dielectric constant experimentally so It'd be good if I could get an accurate result for calculating the resulting capacitance with a dielectric. Also, the last time I tried it with a 3V potential difference, the voltage drops straight...
  9. M

    'Rolled' homemade capacitors

    I also have a valve voltmeter though, but I don't think I could barrow that kind of DMM you're talking about. I'm quite interested how could we do this: "But if you can see any delay at all, compared with the meter without a capacitor, your time constant will be several tens of ms." assumption...
  10. M

    'Rolled' homemade capacitors

    The voltage drops really quick the last time I tried it, I don't think I can measure the time with a stopwatch. Would having a larger capacitor help?
  11. M

    'Rolled' homemade capacitors

    Sorry, I edited it just now lol. I'm quite groggy at this time already. Anyway, your posts were really helpful, thank you. Edit: I really just want to make things clear, I can use the resistance of the voltmeter which is 10 Mega Ohms as the resistance for the time constant equation right? (My...
  12. M

    'Rolled' homemade capacitors

    Ok I get it. I have a digital multitester here do you think it's safe to assume 10MΩ as the deflecting resistance of the voltmeter?
  13. M

    'Rolled' homemade capacitors

    By discharge, do you mean the actual charge of the capacitor or its voltage? Also, by start value, is it the applied voltage or the initial charge? Also, you are talking about \tau = RC where tau is the time constant, R is the resistance, and C is the capacitance. Right?
  14. M

    'Rolled' homemade capacitors

    I tried doing this, and I tried to read the potential difference across the plates after I charged it using a voltage source. I did get some reading, but it diminishes steadily over time, am I doing it right?
  15. M

    'Rolled' homemade capacitors

    Oops, it's polyvinylidene chloride I could've looked that up earlier. Anyways, anyone willing to answer 1?
  16. M

    'Rolled' homemade capacitors

    Is that plastic polyethylene? Sorry, I'm not familiar with materials. I'm asking because I'd also like to look up the dielectric constant of the materials I'm using.
  17. M

    'Rolled' homemade capacitors

    By rolled, I mean this kind of basic homemade capacitors: http://www.ehow.com/how-does_4852927_building-a-capacitor.html Kind sirs, I have few questions regarding this kind of capacitor: 1.) Would I still be able to get the 'theoretical free-space' capacitor of the same dimensions using C_o =...
  18. M

    Homemade capacitors

    ^ Shoot, I didn't take the discharging into account, this is getting more and more complicated. What I actually want to do is to try to measure some dielectric constants from: K=C/C_o I got: K=V_o/V
  19. M

    Homemade capacitors

    Oops yeah, sorry, I know that. Though that was rather, pedantic of you haha. Thanks anyway.
  20. M

    Homemade capacitors

    Yes, it is, thank you. I basically need nylon screws (which I think are really good insulators) to put the two plates together. Another question, are aluminum foils (this is what I have at the moment) the optimal, cheapest, and most convenient conductor for this kind of set up? As...
  21. M

    Homemade capacitors

    You mean I'd connect two aluminum sheets together directly by using nylon screws? Sorry, I can't quite visualize that, I'd be very thankful I you could provide an image with that. I'm sorry if this sounds so imposing.
  22. M

    Homemade capacitors

    I want to make a parallel plate capacitor without dielectric between it, that is, a capacitor with free space. Can I do a working capacitor with just a two parallel cardboard coated in aluminum? I figured it should look like this: Also, if there's anyone who's got a better idea on how I...
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