PHY 2054 Midterm: 2054_Spring12_Exam1-solutions
Document Summary
Exam 1 solutions: two identical conducting spheres a and b carry charges 2q and 3q, respectively. They are separated by a constant distance much larger than their diameters. A third identical conducting sphere c is uncharged. Sphere c is first touched to a, then to b and finally removed. As a result, the magnitude of the electrostatic force between a and b, initially f, becomes. Solution: when c is touched to a, their charges equalize at q apiece. The force between a and b is proportional to the product of the charges, which changes from 6q2 to 2q2, so the force is 1/3 of its original value. 6: electrons in a particle beam have a velocity of 5 ! Solution: the velocity triples, so the final kinetic energy is 9 times larger and thus the work performed by the field is 8 times the initial kinetic energy.
