PHY 2049 Midterm: University of Florida PHY 2049 exam1_sols
Document Summary
Fall 2002: a metal ball is suspended by a string. A positively charged plastic ruler is placed near the ball, which is observed to be attracted to the ruler. The metal ball is either electrically neutral or negatively charged. If the ball is already negatively charged, then it will be attracted toward the ruler. Since both spheres are conductors, the charge on sphere a is able to ow onto b once they touch. In order that the net force on the proton is zero the charge q must be negative. If we call the distance between the electron and proton a, the distance between the proton and q is 3a, so that the force on the proton is. In equilibrium fx = 0; solving for |q|, we nd |q| = 9e, or q = 9e. Using e = 1. 6 10 19 c (something you should remember), then q = 1. 44 10 18 c.
