1. The potential difference between two parallel plates is 1.5 x 102 V. You would have to do 0.24 J of work if you were to move a small charge, in opposition to the electric force, from one plate to the other. Calculate the magnitude of the charge. [1.6 x 10'3 C] 3. A pith ball of mass 1.0 x 1025 kg with a positive charge of 4.0 x 10'? C is slowly pulled at a constant speed by a string a distance of 50.0 cm through a potential difference of 8.0 x 102 V. It is then released from rest and \"falls" back to its original position. (a) Calculate the work done by the string in moving the pith ball. (b) Calculate the magnitude of the average force required to do this work. (c) Calculate the kinetic energy of the pith ball when it arrives back at its original position. (d) Calculate the speed of the pith ball just as it reaches its final position. 5. What is the potential difference required to accelerate a deuteron of mass 3.3 x 10'27 kg and charge 1.6 x 10'19 C from rest to a speed of 5.0 x 105 m/s? [2.6 x 105 v1 Pg37l 1. Figure 9 shows a common technique used to accelerate electrons, usually released from a hot lament from rest. ( This simulator also helps understand the apparatus httpphysicsbuedu!-duf_fwsemester2/c05 Uparallelplatehtml) The small hole in the positive plate allows some electrons to escape providing a source of fast-moving electrons for experimentation. The magnitude of the potential difference between the two plates is 1.2 x '103 V. The distance between the plates is 0.12 m. (a) At what speed will an electron pass through the hole in the positive plate? [2.1 x10"r m/s] (b) Is the electron pulled back to the positive plate once it passes through the hole? Explain your answer. (c) How could the apparatus be modified to accelerate protons? (d) Find the speed of the emerging protons in an appropriate apparatus. [4.8 x '105 m/s]