PHYS 118 Midterm: PHYS118 Midterm 1 Practice with Solution
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19k, can decay by either + emission or . Problem 1 the isotope of potasium with a = 40, 40 emission. A write the complete decay process for this isotope for both cases, + and . Answer: the masses in the table are atomic masses, and we need to compare nuclear mass. We can ignore electron binding energy and neutrino masses. Answer: 1g of 40k is 1/40 mole = 1. 5 10 24 atoms. The number of decays per second is -1 times the derivative of n . = noe t = no at t = 0, where = (3) Answer: at t = 1 109y, and using exactly the equation from above, Determine the electric eld at r, ~e(r), where. A: r < r1; ~e = 0 since there is no enclosed charge. B: r1 < r < r2; charge on the innermost sphere is all that matters. C: r2 < r. charges from both spheres contribute.
