Recent content by izzy93

  1. I

    Graduate Error propagation - partial derivative?

    Yes I had the θ error in degrees JTBell! oops Thankyou Tom K, I finally got the errors from both formulas matching!
  2. I

    Graduate Error propagation - partial derivative?

    thanks Tom_k - So when I compute cos of theta (the bragg angle which has an associated error) the error in it is just the error in theta? Even When I put that value in the ordinary error propagation equation, it does not come out equal to the errors in the partial derivatives: z= B*Cosθ then...
  3. I

    Graduate Error propagation - partial derivative?

    Hi jtbell, thanks for your response. I have an error in θ and also worked out the error in cosθ as Δcosθ = sinθ Δθ. the thing is partial derivative formulas (which give the same result) gives me a much larger error compared to the other one, so I'm inclined to go with that one...
  4. I

    Graduate Error propagation - partial derivative?

    I am getting a little confused on which error propagation to use: I am looking to calculate the error in B*Cos(θ) , for the vertical axis of a williamson hall plot. where B is fwhm of a peak with it's own error and cos of the bragg angle I am unsure of whether i need to use partial derivative...
    • izzy93
    • Thread
    • Analysis Derivative Error Error propagation Partial Partial derivative Propagation
    • Replies: 9
    • Forum: Other Physics Topics
  5. I

    Calc Mass of Earth for Hydrogen Atmos Retention

    Homework Statement calculate approximately how much more massive the Earth would have to be before it could retain a significant hydrogen atmosphere, assuming the Earth’s density to be the same as its current value. Homework Equations Temperature limit to retain hydrogen in the Earth's...
  6. I

    Solid state physics, lattice constants, ionic radii, nacl

    Homework Statement NaCl (a0 = 5.64A° ), NaBr (a0 = 5.98A° ) and KCl (a0 = 6.30A° ) all have the same structure, which is the NaCl structure. (a) Assuming the spacings are determined by the ionic radii of the relevant ions, what would value would you expect for the lattice constant of...
  7. I

    Quantum, Spin, Orbital Angular momentum, operators

    Homework Statement If a particle has spin 1/2 and is in a state with orbital angular momentum L, there are two basis states with total z-component of angular momentum m*hbar l L,s,Lz,sz > which can be expressed in terms of the individual states ( l L,s,Lz,sz > = l L,Lz > l s,sz > ) as l...
  8. I

    Capacitors, potential difference, electric displacement

    Question: Considering a parallel-plate capacitor that has a slab of dielectric with relative permittivity epsilomd = 5 and thickness d = 2 mm occupies half of the gap. The half is air with relative permittivity epsilom2=1 Denoting the electric field, and electric displacement in the...
  9. I

    Graduate F = del(p.E) and F = (p.del)E are equivalent

    Question: In the electrostatic case, the expressions F = del(p.E) and F = (p.del)E are equivalent: I am having trouble with how to show they are equivalent In the second equation, I expanded it out to give F= px (dE/dx) + py (dE/dy) + pz(dE/dz) Any help as to how to do this would be...
  10. I

    Undergrad Estimate Probability of Excel Data Analysis Results

    Hi, I've come up with a solution I think. Going to use the NORM.DIST function thanks for the reply though
  11. I

    Undergrad Estimate Probability of Excel Data Analysis Results

    Not sure where to post this question, but here goes In excel I have calculated the average annual rain for the period 1990-2012 to be 50.2mm . How do you estimate the probability that this measured average (1990-2012) is consistent with the long term mean annual rain for the period 1948-2012...
  12. I

    Undergrad Solving Eigenvalues: Complex Numbers Solutions

    Thanks, Just wondering for λ1=i-1 = √2 e^i(3∏/4) , I get the angle phi to be -∏/4 so if the angle is negative do you take it as a rule to add on ∏?
  13. I

    Undergrad Solving Eigenvalues: Complex Numbers Solutions

    I have solutions for eigenvalues to be λ1=i-1 = √2 e^i(3∏/4) and λ2=i+1 =√2 e^i(∏/4) How do you go from the i-1 to the next bit for both? Thanks
  14. I

    Mathematica How can I write a Mathematica function that handles different argument types?

    Thanks for all you're help, Think I got it now
  15. I

    Mathematica How can I write a Mathematica function that handles different argument types?

    ff[a_] := Which[IntegerQ[a], Abs[a], Element[a, Reals], If[a < 0, 0, IntegerPart[a]], Element[a, Complexs], {Abs[Round[Re[a]]]} && Abs[Round[Im[a]]]] It now works for getting the real number rounded to the nearest integer if positive.It doesn't make it 0 if -ve though. As far as I can...