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ans

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  1. I'm planning an investigation on how magnetic flux density midway between opposite poles of 2 bar magnets varies with separation of the bar magnets (using a Hall Probe). [simply as shown in attachment] To do this, I'll need to calibrate a hall probe (which I think is done by working out the p.d. (Hall pd) at a known magnetic field strength). My initial thoughts were that I could use a long straight wire of known current, and use [math] B \ = \ \frac{\mu_0 I }{2 \pi \ r} [/math]however, this would not work would it? Due to non-uniform magnetic field. Is the best approach to use a "Helmholtz coil" to get a uniform field- and use the formula given here: http://en.wikipedia.org/wiki/Helmholtz_coils ? I've never come across this before, so any help / hints would be appreciated. Thanks. PS - I apologise in advance if this thread is better suited elsewhere.
  2. ans

    Schiavo case

    Selfish for what? Endeavouring to fulfil his dying wife's wishes? One could argue it is the blood family that's being selfish - for wanting their daughter to live on, simply prolonging the imminently inevitable death.
  3. Know the forumulae: mr = mass/mole (for solids) conc. = mol/dm^3 (for aq solutions) mol = vol/24dm^3. (gases) Type out an example question and it will make someone can help explain easier.
  4. what I'm unsure of is if [math]m=m_o.\gamma[/math] and if the rest mass of a photon = 0, then relativistic mass=0? Also when considering a photon, v=c, the relativistic formula doesn't make sense. ie [math]\gamma = \frac {1}{\sqrt{c^2-v^2}}[/math]
  5. Maybe assuming there is friction, air resistance (ie there is an opposing force) or perhaps is it something to do with the pull of the trailer on the car??
  6. ans

    natural log prob

    y - lnx = 8 3x + y = 1 y=(8+lnx) 3x+ (8+lnx) = 1 => 3x+lnx=3....(1) exponential of both sides of (1): [math]e^{3x+lnx} = e^3[/math] equate coefficients x=1 if x=1, y-ln1=8 so y-0=8 y=8
  7. Well in simple terms I'd assume it's basically monitoring and observing for any physiological side effects. However, if none are seen, then obviously the drug is not assumed to safe for humans, as more clinical trials need to be done??
  8. If not reproductive cloning, then maybe for drug/chemical testing?
  9. Conditions required for dynamic equilibria -a closed system -reversible reaction -rate of forward reaction = rate of backward reaction -concentration of reactants and products do not change.
  10. ans

    Differentiation

    In simple terms is it correct to say that what determines what stem cells differentiate into is their environment (eg chemicals around the cell)
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