

Need to clear up a few things for my A2 exam

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    There are some things I do not understand in my book and I have no opportunity to ask my teacher before the exam so any contribution to any of the following will be much appreciated:

    When identifying ions in mass spectrometers via their mass to charge ratios, my book says the velocity of the ions after passing through the electric field can be controlled by the user via variation of the electric field strength, but how can the acceleration of the ion in the electric field (and hence its velocity) be known when the effect the electric field has on this is based on the charge of the ion, which would not be known?

    Is Faraday's Law that induced e.m.f is directly proportional to rate of change of magnetic flux or magnetic flux linkage? If it is proportional to flux, is e.m.f = flux linkage? (My book contradicts itself with this)
    And Lenz's Law: e.m.f = - rate of change of flux or flux linkage?

    Is it true that IpVp = IsVs in general for transformers?

    For mass-energy equivalence, is it that the separate masses of all the nucleons - mass of combined nucleus = mass defect = total binding energy holding it together = energy released in formation of nucleus?

    When calculating energy released in a nuclear reaction, is it change in mean average binding energy per nucleon multiplied by total number of nucleons involved or just the ones that were combined before/after?

    My book says that in X-ray attenuation through matter Compton Scattering occurs for photons with 0.5-5 MeV of energy and pair production (into electron-positron pair) occurs for >1.1 MeV. As you can see these ranges overlap, so how do you determine which occurs when they overlap or is one of them wrong?

    In MRI, protons can switch from parallel to antiparallel alignment via emission or absorption of a specific amount of energy. Which change for emission and which for absorption?

    In PET scanning, distribution of radioactivity matches up with metabolic activity because more is absorbed by cells doing more work. In which areas will more radiation be detected, the ones with higher metabolic activity where it is absorbed more or the the other way around?

    Is the equation for the density of the universe in terms of the Hubble constant for the AVERAGE density of the universe or the CRITICAL density and which notation corresponds to which? rho_0 / rho_c ?

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    Har har har


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Updated: June 17, 2012
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