Question

5. As shown in Figure 5.1, three large, thin, uniformly charged plates are arranged so that there are two adjacent regions of uniform electric field. The origin is at the center of the central plate. + A Location A is (-0.4,0,0) m, and location B is (0.2,0,0) m. The electric field Ei has the value (725,0,0) V/m, and E2 is (-425, 0, 0) V/m Figure 5.1 a. Consider a path from A to B. Along this path, what is the change in electric potential? b. What is the change in electric potential along a path from B to A? c. There is a tiny hole in the central plate, so a moving particle can pass through the hole. If an electron moved from A to B along the path shown, what would be the change in its kinetic energy? d. What is the minimum kinetic energy the electron must have at location A in order to ensure that it reaches location B?

Answer 1

a) VA - VB = -E1*dx1 + E2*dx2

= -725*0.4 + 425*0.2

= -205 V

b) VB - VA = -(VA - VB)

= 205 V

c) change in kinetic energy = Workdone

= q*delta_V

= -1.6*10^-19*(VB - VA)

= -1.6*10^-19*205

= -3.28*10^-17 J

d) minimum kinetic energy = -Workdone

= 3.28*10^-17 J