PHY 252 Test 1 Fall 2012 Show your work on the paper provided in a manner easy to follow. Write equations, show units in each step; work without units will not be graded. Provide drawings where appropriate. Circle your answers on your worksheets. Do not expect partlai credit for a wrong answer and no work shown. 3' ll. 1. Three charges. equal to +3Q, +2Q and {1 are located a distance a from (SFBQ the origin as shown in the figure. The point P is at the origin. _. af a. {4 pts] What are the x and y components of the electric field E at 'Q JP +2Q point P? 0: _a_'e_' X a. E: Er: b. {3 pts] What is the electric potential energy of the configuration of three charges? b. c. {3 pts] What is the electric potential at point P? c. d. {3 pts} Afourth charge with charge +3Q is slowly moved from infinity to point P. How much work must be done by an external agent in this process? d. 2. {4 pts] A uniform linear charge of 3.0 nCr'm is distributed along the y axis from y = 3 m to y = 2m. Which of the following integrals is correct for the magnitude of the electric field at y = 4 m on the y axis? Show a diagram. Circle the correct answer. 3 2?er 1 :izhr 3- I . - .1 d- . : --" i-'-l -_y. 4 1o - 3' 4 gig). b. I _ 1 e. none of these -5 lo'v' 5' 235$ ' I:- I J'h -3 r4 - y