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qsx

  • one year ago

1. Each plate of a parallel plate capacitor measures 12.0 cm by 18.0 cm. The plates are separated by a distance d = 1.80 mm of air. A 9.00 V battery is connected to the plates. The positive (+) battery terminal is connected to the positive (+) plate and the negative (-) battery terminal is connected to the negative (-) plate. (a) What is the capacitance of the capacitor? (b) What is the charge on the capacitor? (c) How much energy is stored in the capacitor? (d) What is the electric field between the capacitor's plates?

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  1. theEric
    • one year ago
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    I referred to this link: http://www.electronics-tutorials.ws/capacitor/cap_1.html I found that the formula is\[c=k\left(\frac{A}{d}\right)\]

  2. theEric
    • one year ago
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    \[C=k\left(\frac{A}{d}\right)\]

  3. qsx
    • one year ago
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    what will be the answers with working and formulas

  4. theEric
    • one year ago
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    I think all the more I can tell you is that I think \[ k=\frac{1}{(4\pi)(\epsilon_{relative, air}\times \epsilon_0)}=\frac{1}{(4\pi)(1.00059\times 8.85418782 \times 10^{-12})}\]

  5. theEric
    • one year ago
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    That will let you solve for capacitance.

  6. theEric
    • one year ago
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    Then the charge, \(Q\), you can get from \(Q=C\ V\), which is the rearranged definition of capacitance, where \(C=\Large\frac{Q}{V}\).

  7. qsx
    • one year ago
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    i will try, it would be great if i get answers so i can compare to my working

  8. qsx
    • one year ago
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    @Festinger

  9. qsx
    • one year ago
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    @theEric

  10. theEric
    • one year ago
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    I don't know what to do about parts C and D, sorry! All I'm certain of is that that link is probably truthful! Good luck!

  11. qsx
    • one year ago
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    ima try my best lol, thanks for the help :)

  12. shamim
    • one year ago
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    i think capacitance of a capacitor is c=k(A/d) and k=aphcilon not

  13. shamim
    • one year ago
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    for ur question c energy stored in capacitor is u=(1/2)cv^2

  14. shamim
    • one year ago
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    now for ur question d electric field E=v/d

  15. shamim
    • one year ago
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    for ur question c energy stored in capacitor is u=(1/2)cv^2

  16. shamim
    • one year ago
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    i think capacitance of a capacitor is c=k(A/d) and k=aphcilon not

  17. Festinger
    • one year ago
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    Different books and people use different symbols. Here are some holy grail of equations for Capacitors: \[C=\frac{Q}{V}\] or \[Q=CV\] Which says the charge on a capacitor is the product of it's capacitance and the potential difference. The capacitance is a measure of how well the capacitor holds charge. High capacitance means for the same potential different, it can hold more charge. Because of how Capacitance is defined, and for geometries which give nice potentials, in this case parallel plate capacitors, we can express capacitance purely by the geometry: \[C=k\epsilon_{0}\frac{A}{d}\] Where A is the area, d is the distance between the plates. ϵ0 is the permittivity of free space and k is something called the dielectric constant, which depends on what is between the plates. For air or vacuum it's 1. The potential energy U stored in the capacitor is then: \[U=\frac{Q^{2}}{2C}\] If I substitute the equations from above Q=CV, I get 2 more forms, use whichever you prefer: \[U=\frac{Q^{2}}{2C}=\frac{1}{2}CV^{2}=\frac{1}{2}QV\] Since there is energy stored between the plates, I can find the energy density, which can be related by Electric field. \[u=\frac{U}{V}=\frac{U}{Ad}=\frac{1}{2}\epsilon_{0}E^{2}\] Now to solve. For (a): \[C=k\epsilon_{0}\frac{A}{d}=\frac{0.0216\epsilon_{0}}{0.0018}\:F\] F is farads, the unit for capacitance. (b) Charge. Q. Q=CV! \[Q=\frac{0.0216\epsilon_{0}}{0.0018}*9=9.56*10^{-10}Coulombs\] (c) Energy! U! \[U=\frac{1}{2}QV=9.56*10^{-10}*\frac{9}{2}=4.3*10^-9J\] (d) E. Solve for E! \[\frac{U}{Ad}=\frac{1}{2}\epsilon_{0}E^{2}\] My calculations might be wrong, but the equations should be correct.

  18. Festinger
    • one year ago
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    E should be 4999 V/m

  19. qsx
    • one year ago
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    Thankyou every one, i have few more questions which i will post

  20. qsx
    • one year ago
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    I want anyone to confirm the answers plz

  21. qsx
    • one year ago
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    @theEric

  22. theEric
    • one year ago
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    I'll look for them when you post them! And I'll help if I can.

  23. qsx
    • one year ago
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    2. Two horizontal conducting rails are connected by a resistor R = 0.750 Ω, as illustrated below. There is a uniform magnetic field B = 0.120 T pointing vertically downward. A conducting rod of length l = 2.20 m moves to the left along the two rails at a constant speed v = 3.90 m/s. Assume that resistance between the rod and rails is negligible. (a) What is the induced emf in the circuit? (b) What is the magnitude and direction of the current flow? (c) What is the rate of heat dissipation in the resistor? (d) What force is required to keep the rod moving at its constant speed?

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  24. qsx
    • one year ago
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    3. An object with height ho = 4.8 mm is placed upright a distance s0 = 16 cm from the center of a concave mirror. The image is located a distance si = 7 cm from the center of the mirror. (a) What is the focal length of the mirror? (b) What is the size and orientation of the image? (c) Where should the object be placed so that the image size is the same as the object size? (d) What are the image distance and the magnification when the object is placed at a distance s0 = 4.1 cm from the center of the mirror?

  25. qsx
    • one year ago
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    4. A photosensitive metal is illuminated by monochromatic light with a wavelength λ = 550 nm. Electrons are emitted due to the photoelectric effect. Here are some constants that might be helpful: 1 eV = 1.60 x 10-19 J Speed of light = 3.00 x 108 m/s Plank’s constant = 6.63 x 10-34 J s Mass of an electron = 9.11 x 10-31 kg (a) If the work function of the metal is  = 1.8 eV, what is the maximum kinetic energyof an emitted electron? (b) If the work function of the metal is  = 1.8 eV, what is the maximum speed of anemitted electron? (c) What is the threshold (or cutoff) frequency of the metal? (d) If the photosensitive metal is illuminated with light having a frequency equal to thethreshold frequency, what is the theoretical maximum kinetic energy an emitted electron can have?

  26. qsx
    • one year ago
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    I need it with working, plz plz, it is due before sunday midnight

  27. qsx
    • one year ago
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    @radar @Festinger @theEric

  28. theEric
    • one year ago
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    Please post these as separate questions so that the people working on it get credit and so that other people can see these and have a chance to answer them. Also, I think OpenStudy permits just one question at a time, which is all we can work on anyway, @qsx .

  29. qsx
    • one year ago
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    ohh, so we do one by one, i will post 2nd on the after i finish first, Thank for letting me know, new user.

  30. theEric
    • one year ago
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    Haha, not a problem at all :)

  31. theEric
    • one year ago
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    And hopefully there are people who can help. So you're still working on this one?

  32. qsx
    • one year ago
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    right now i am doing work for a different class, i will get back to it soon

  33. theEric
    • one year ago
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    I see! Good luck! :)

  34. qsx
    • one year ago
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    Thankyou :)

  35. radar
    • one year ago
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    As it has been pointed out there are different formulas you may use and @theEric has provided an excellent link which you can reference. my old books gave this formula (which I believe is the same as theEric provided:|dw:1374787084437:dw| Using this then you would calculate the capacitance as:\[(8.85\times10^{-12})(18\times10^{-2}\times12\times10^{-2})\over1.8\times10^{-3}\]\[C _{o}=106.2\times10^{-12} \]Or 106.2 pF Did you get something like that?

  36. radar
    • one year ago
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    If you are pursuing an Electrical Engineering career you have a lot of work to look forward to. It will be worth it. Good luck with it.

  37. theEric
    • one year ago
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    @radar I read your "About Me" thing, and it's all cool and admirable! Is that an area of electrical engineering? Also, is \(\epsilon_0\) used only for free space between the plates?

  38. radar
    • one year ago
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    yes air, if someother dielectric is used like Mica, then you adjust by multiplying by 5 and use \[\epsilon _{r}\]\[\epsilon _{r}=5\epsilon _{o}\]

  39. radar
    • one year ago
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    @theEric I never obtained a college EE degree, but I converted to an Electronics Engineer in my government career, becoming classified as GS 855-**. Years prior I was an electronic tech GS-856 Those numbers are U.S. government classifications of job titles. Most of the time I worked with radar. But have retired and don't do much anymore.

  40. radar
    • one year ago
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    I am going to check out those links you posted

  41. radar
    • one year ago
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    I noticed that the latter link gave Mica a 3-6, my old text gave it a 5, (which is within the range.

  42. radar
    • one year ago
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    @theEric I just got through reading your profile, I would of guessed you were going for an EE, but computer science does include the hardware (or at least I think it does) and I believe you will become involved in the electronics area.

  43. qsx
    • one year ago
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    Thank yuo :)

  44. qsx
    • one year ago
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    after all working i ended up with this (a) The capacitance of the capacitor C = OA/d Where, O=8.85*10-12 , A=Area of plate , d=distance between plates C = 8.85*10-12*(18*12)*10-4/(1.8*10-3) = 1.062*10-10 F (b) Charge on the capacitor Q = C*V = 1.062*10-10 *9 = 9.558 *10-10 C = 9.558*10-4 C (c) Energy is stored in the capacitor = *C*V2 = * 1.062*10-10 *92 = 4.301*10-9 =4.301*10-3 J (d)The electric field between the capacitor plates = V/d = 9/(1.8*10-3 ) = 5*105 V/m

  45. qsx
    • one year ago
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    @Festinger

  46. Festinger
    • one year ago
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    E=5000 V/m

  47. Deba_001
    • one year ago
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    (a) C=ε 0 A /d =\[8.85x10^{-12}\]x0.0216/.0018=106.2 pF, (b) Q=9X106.2 pC=955.8pC (c) U = \[1/2 C V ^{2}\] = 1/2 X 106.2* 81 pJ=4301.1 pico Joule (d) E = V/ d = 9 /.0018 = 5000 N/C

  48. qsx2
    • one year ago
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    @Fifciol

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