1. How do we detect gamma rays?

18. Review: What is each peak? Why are they there? Calculate the location of the Compton edges and backscattering! 1.17 MeV and 1.33 MeV

19. Five Minute Questions Review gamma spectroscopy data Photoelectons Compton Edge Back Scattering Pair Production X-ray Production Simple models of atoms – Evolution in our thought … Thompson’s plum pudding model – photon spectrum? Rutherford Scattering Bohr’s atom in all its glory X-ray spectra

20. Five Minute Question #1. Gauss’ Law You have sphere of uniform charge. (The charge is spread out evenly throughout the sphere.) The charge is Q. The radius is R. What is the Electric Field strength at point A where the distance from A to the center of the sphere is r A (r A > R). What is the Electric Field strength at point A where the distance from A to the center of the sphere is r B (r B = R). What is the Electric Field strength at point A where the distance from A to the center of the sphere is r C (r C < R).

21. Five Minute Question #2 Start the calculation to find the radius of orbit of a geosynchronous satellite. (Start with Newton’s second Law. Then use Newton’s law of Gravity and centripetal acceleration!)

22. Chapter 6 – Based on experiments, how can we learn about atoms and their internal structure? Model #1 – Plum Pudding What force does a raisin (q=-e) at a radius, r, feel from the pudding? Attractive to center No force at the center Oscillatory – specific frequency