8. Calculate the electric field at point Z in Figure 5, due to the point charges q, = 5.56 X 10-9 C at point X and 42 = -1.23 x 10 9 C at point Y. 91 92 0.668 m 0.332 m- X Y Z Figure 59. An electron enters a uniform electric field of 145 N/C pointed toward the right. The point of entry is 1.5 m to the right of a given mark, and the point where the electron leaves the field is 4.6 m to the right of that mark. TA A (a) Determine the change in the electric potential energy of the electron. (b) The initial speed of the electron was 1.7 x 10' m/s when it entered the electric field. Determine its final speed. . . An old television cathode-ray tube creates a potential difference of 1.6 x 10* V across the parallel accelerating plates. These plates accelerate a beam of electrons toward the target phosphor screen. The separation between the plates is 12 cm. /u TA (a) Using the principle of energy conservation and the definition of electric potential difference, calculate the speed at which the electrons strike the screen. (b) Calculate the magnitude of the electric field. I 11. Three charges, q, = +6.0 x 10- C, 92 = -3.0 x 10-6 C, 93 = -3.0 x 10 6 C, are located at the vertices of an equilateral triangle (Figure 5). kru TA (b) Calculate the total electric potential energy of the group of charges. 3.0 m 42 43 Figure 5 12. Two protons move toward each other. They start at infinite separation. One has an initial speed of 2.3 X 10 m/s, and the other has an initial speed of 1.2 x 105 m/s. Calculate the separation when the protons are closest to each other. K/u Till