PH 126 Midterm: ph126_F09_Exam_1
Document Summary
Ph126 exam i: solve two of the four problems below. All problems have equal weight: clearly mark your which problems you have chosen using the tick box, you are allowed 1 sheet of standard 8. 5x11 in paper and a calculator. Four positively charged bodies, two with charge q and two with charge q, are connected by four unstretchable strings of equal length. In the absence of external forces they assume the equilibrium con- Note: this can be done in two ways. You could show that this relation must hold if the total force on each body, the vector sum of string tension and electrical repulsion, is zero. Or you could write out the expression for the energy u of the assembly and minimize it. An electric dipole in a uniform electric eld e is displaced slightly from its equilibrium position, as shown above. The angle between the dipole axis and the electric eld is (you may assume is small).
