1 Homework 4 1. Two infinitesimally small point charges of +2.0 μ C each are initially stationary and 5.0 m apart. (a) How much work is required to bring them to a stationary position 2.0 m apart? (b) 2.0 mm apart? (c) With a finite amount of energy, is it possible to push them together? 2. Beginning in 1906, Ernest Rutherford carried out a famous series of experiments at McGill University in which he bombarded thin gold foil with alpha particles having a mass of 6.68 × 10-27 kg and a charge of +2 e . Most of the particles whizzed right through the foil, some were slightly deflected, and a very few were bounced (or "scattered") straight back. These results led him to speculate that every gold atom consisted of a tiny, compact, positively charged "nucleus" surrounded by a relatively huge volume of practically empty space, whose extent was defined by the orbits of its circling electrons. If an alpha particle is fired from a very distant source with an initial speed of 2.25 × 10 7 m/s, straight at the nucleus of a gold atom, having a charge of +79
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This note was uploaded on 05/06/2008 for the course PHYS 1304 taught by Professor Ye during the Spring '08 term at SMU.