Recent content by L-x

  1. L

    Helping students transition from High School to University

    I am in the rather unique and exciting position of being able to design an extension curriculum for some gifted Physics students who are in their final year of high school. The goal of the curriculum is to help prepare them for university physics with tools and ways of thinking, without just...
  2. L

    Snell's law question with a twist...

    Thanks! I can see now that as the ring falls deeper, the angle light from the ring makes with the boundary between the two media approaches 90, and therefore the angle that the light ray makes with the other side of the boundary approaches the critical angle.
  3. L

    Snell's law question with a twist...

    Homework Statement https://gyazo.com/f8cf156e7bd2f2511e3fa859e3732fe6 Homework Equations Snell's law. The Attempt at a Solution I'm mostly confused about the relevance of the second medium (of index n2) given that the distance between the ring and the boundary is "small". Having attempted to...
  4. L

    Studying Share self-studying mathematics tips

    Hi all, I'm a physics graduate now working as a maths and physics teacher in a sixth form college. I loved my degree, though wish I'd had the work ethic I do now when I was studying full time. I took a theoretical physics course in my 4th year (syllabus here...
  5. L

    Springs in Series & Parallel

    What OCR wants to get at is that if you have a wire of some dimensions, doubling the length halves k without affecting YM, and having two wires (effectively doubling the cross sectional surface area) doubles k without affecting the YM. This lets you nicely draw a distinction between the YM of a...
  6. L

    What happens when a particle and an anti particle collide

    That's precisely the point I was trying to make.
  7. L

    What happens when a particle and an anti particle collide

    The technical difference between virtual and real particles is that virtual particle are "off shell" meaning that their mass energy and momentum does not satisfy the relation E^2 - P^2 = M^2, however virtual particles should be thought of as a sort of mental abacus that help us calculate things...
  8. L

    What happens when a particle and an anti particle collide

    I'd be fascinated to know how one could estimate the volume of matter in the universe without using the method I outlined above. I'd also be interested to know how you came up with that percentage.
  9. L

    What happens when a particle and an anti particle collide

    Scientists have indeed, and you're thinking along nearly the right lines: cosmological observations allow scientists to make a reasonable estimate of the energy density of matter in the universe, and calculating the volume of the observable universe is straightforward (though interestingly, due...
  10. L

    What happens when a particle and an anti particle collide

    "I think it's possible in principle - just very very difficult." very very difficult is an absurd underestimate. Producing and containing 1kg of antimatter is "possible in principle" in the same way that counting every particle in the observable universe is "possible in principle".
  11. L

    Resistance of a wire with changing radius

    R =\frac{x \rho}{A}=\frac{x \rho}{\pi r^2}=\frac{x \rho}{\pi a^2 e^{2bx^2}} Are you sure your expression for dR is correct?
  12. L

    Muonic hydrogen, change in potential of the muon.

    Thanks. That makes sense.
  13. L

    Resistance of a wire with changing radius

    Remember that A is a function of r when you try to work out dR
  14. L

    Muonic hydrogen, change in potential of the muon.

    Homework Statement Taking the proton to be a uniformly charged sphere of radius 1 fm, find an expression for the change in potential experienced by the muon as compared with that in the case of a point-like proton. Use first order perturbation theory to calculate the ground-state energy...
  15. L

    * * (Exam tomorrow morning!)

    *URGENT* (Exam tomorrow morning!) Calculating a real integral using residue theorem Homework Statement See attached picture http://imageshack.us/photo/my-images/827/unledozs.jpg/ Homework Equations The Attempt at a Solution Parts a) and b) are straightforward. For b) I end up...
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