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  1. J

    Poiseulle's law

    Hi; Could someone please help me with this question: "Suppose you have measured the flow rate for a number of tubes with different lengths but the same radius, how would you graph your data to test Poiseulle's law (Hint: choose the scales of the axes so that the theoretical graph is a straight...
  2. J

    Law of reflection and refraction

    Hi; I was wondering if someone could please help me with this question: "When you measure the law of reflection and the law of refraction, what is the advantage of making 2 measurements: one clockwise from the normal and one counterclockwise from the normal?" Could an advantage be that this is...
  3. J

    Bohr model of atom

    Ok, so I find the energy change by doing E of upper state - energy of lower state right? So I get (-0.2) - (-0.5) = 0.3 After I find this energy change, how do i find the decrease in mass? If I use E=mc^2, I plug in 0.3 into E and 1.00794 into m? What am I solving for? I'm confused. Thanks...
  4. J

    Bohr model of atom

    I guess so. That's what confuses me about the question. I don't know how to incorporate the mass into it. Does anyone know how to do this? Thanks.
  5. J

    Bohr model of atom

    Hi; Could someone please help me with this question: By what fraction does the mass of an H atom decrease when it makes an n=7 to n=5 transition? How would I go about this question? Thank you.
  6. J

    Angular Magnification

    Hi; Could someone please help me with this question: A small insect is placed 5.37 cm from a +5.84 cm focal length lens. a) Calculate the position of the image. b) Calculate the angular magnification. For part a I used the lens equation 1/f = 1/d object + 1/d image, and I the position of the...
  7. J

    Wave Nature of Light

    HI; Could someone please help me with this question: Calculate the minimum thickness needed for an antireflective coating (n=1.35) applied to a glass lens in order to eliminate blue (458 nm) reflections for light at normal incidence? How would I go about this question? Thanks.
  8. J

    Waves- Interference/Double-slit experiment

    Hi; Could someone please help me with the following question: In a double-slit experiment it is found that blue light of wavelength 460 nm gives a second-order maximum at a certain location on the screen. What wavelength of visible light would have a minimum at the same location? Can i use the...
  9. J

    Mirror question

    Hi; Could someone please help me with the following question: The image of a distant tree is virtual and very small when viewed in a curved mirror. The image appears to be 18.8 cm behind the mirror. What is its radius of curvature? (Use positive for concave and negative for convex). Would I...
  10. J

    Galvanometer question

    Are you saying to do 0.264 x 36.8E-6? Because that doesnt give me the right answer. Thanks.
  11. J

    Galvanometer question

    Hi; Could someone please help me with the following question: If the restoring spring of a galvanometer weakens by 26.4% over the years, what current will give full-scale deflection if it originally required 36.8uA? Thanks for your help.
  12. J

    Voltage question

    Voltage question.... Hi; Could somebody please help me with the following question: Suppose you want to run some apparatus that is 62.3 m from an electric outlet. Each of the wires connecting your apparatus to the 120 V source has a resistance per unit length of 0.00600 ohms/m. If your...
  13. J

    Nerve conduction question

    I'm not sure about the resitivity, but would this help: That the concentration of Na+ inside axon is 15 mol/m^3 and the concentration of Na+ ouside axon is 140 mol/m^3. And the area of a cylinder (like the axon) is 2(pi)(r)(L).
  14. J

    Nerve conduction question

    Um I'm thinking that I will have to use this equation: R= resitivity*L/A, and therefore I need that 12 cm to use as my length and the diameter to use as my area. I'm guessing I can use this equation to solve for R, but than how do I use the rate? That is what confuses me. Thanks.
  15. J

    Nerve conduction question

    The axon... Hi; The axon is sort of like a tube, because impulses travel through the cell by coming in from small tube like appendages called dendrites, into the cell body, and than travel out via the axon...which is like a long tail. Signals are received by the dendrites and are propagated...
  16. J

    Nerve conduction question

    Hi; Could somebody please help me with the following question: During the action potential, Na+ ions move into the cell at a rate of 3.03E-7 mol/m^2*s. How much power must be produced by the "active Na+ pumping" system to produce this flow agaisnt a +33.9 mV potential difference? Assume that...
  17. J

    Electric Potential and a capacitor

    thanks Thanks a lot for your help, I understand it now.
  18. J

    Electric Potential and a capacitor

    Hi; Could someone please help me with the following question: A huge 4.0 F capacitor has enough stored energy to heat 2.5 kg of water form 21 degrees celsius to 95 degrees celsius. What is the potential difference across the plates? Could i use the equation: PE = 1/2 CV^2. However, I do not...
  19. J

    Electric Field

    Hi; Could someone please help me with this question: An electron (m= 9.11E-31 kg) is accelerated in the uniform field E (E= 1.45 x 10^4 N/C) b/w two parallel charged plates. The separation of the plates is 1.10cm. The electron is accelerated from rest near the negative plate and passes...
  20. J

    Physics Question

    Thanks... Thanks guys, I figured this one out.
  21. J

    Electric fields and dry air

    Hi; Could somebody please help me with the following question: Dry air will break down and generate a spark if the electric field exceeds about 2.90E+6 N/C. How much charge could be packed onto a green pea (diameter 0.800 cm) before the pea spontaneously discharges? The formula i used was...
  22. J

    Physics Question

    Hi; Could somebody please help me with this question: A 3.0g copper penny has a postive charge of 38uC. What fraction of its electrons has it lost? The method I tried was: (3g/63.55g) x 6.02E23 x A(what i'm solving for) = 38xE-6. Than I took my answer and divided it by 29. However this will...
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