6. Free-Response Questions Five charged particles are equally spaced around a semicircle of radius 100 mm, with one particle at each end of the semicircle and the remaining three spaced equally between the two ends. The semicircle lies in the region y > 0 of an xy-plane, such that the complete circle is centered on the origin. Each particle carries a charge of magnitude 6 nC. (Give all direction angles with respect to the +x-axis) +9 O +9 -q -q a. Draw and label a diagram that includes all electric field vectors at point 0. Include x- and y-components if necessary. b. Calculate the magnitude and direction of the net electric field E at point 0. c. If a 2 nC-charge is placed at point 0, calculate the magnitude and direction of the electric force Ⓡ that it experiences.

An object has a charge of 35 nC. How many excess protons does it have?

A proton is fired from very far away directly at a fixed particle with charge q = 1.28 1018 C. If the initial speed of the proton is 2.4 105 m/s, what is its distance of closest approach to the fixed particle? The mass of a proton is 1.67 1027 kg.

Two particles with charges q1 and q2 are separated by a distance d, and each exerts an electric force on the other with magnitude FE. a. In terms of these quantities, what separation distance would cause the magnitude of the electric force to be halved? b. In terms of these quantities, what separation distance would cause the magnitude of the electric force to be doubled?