1. When a nearby charged object causes a change in the distribution of charge on a neutral object, this is called an induced charge separation. Is it possible to create an induced charge separation on an insulator? On a conductor? Explain your answers. 2. The leaves of an electroscope will repel each other if you touch the electroscope with a positively charged glass rod. Use a series of charge diagrams to explain what happens and why the leaves repel each other. 3. Two neutral metal spheres on wood stands are touching. A negatively charged rod is held directly above the top of the left sphere, not quite touching it. While the rod is there, the right sphere is moved so that the spheres no longer touch. Then the rod is withdrawn. Afterward, what is the charge state of each sphere? Use charge diagrams to explain your answer. 4. Two identical metal spheres have different charges. One has a charge of +10 C and the other has a charge of 20 C. If the spheres are allowed to touch each other for a time and then are moved away from each other, what is the final charge on each sphere? Explain 5. A 1.8 g (0.0018 kg) pith ball is suspended from a thread and placed in an electric field. When placed in the electric field, the pith ball is deflected to the left so that the thread makes a 9.5 angle with the vertical. Calculate the electrostatic force on the pith ball. (0.0030 N) Charged rod :oulomb's Law and Electric forces 6. In a hydrogen atom, an electron is 5.29 x 10':[1 m from a proton. An electron has a charge of -1.60 x 10' 19 C, and the proton's charge is +1.60 x 1019 C. Calculate the electrostatic force of attraction acting on the two charges. (8.22 x 10'8 N [attraction]) 7. The electric force between two charged objects is 5.2 x 10'4 N when the objects are 3.11 x 10'1 m apart. What is the electric force between the same objects if the distance is changed to 4.04 x 10'1 m? (3.1 x 10'4 N) BeLearn Physics 30 Module 3 Assignment September 2020 8. A metal sphere with a negative charge of 3.00 [LC is placed 12.0 cm from another similar metal sphere with a positive charge of 2.00 [AC The two spheres momentarily touch, and then return to their original positions. Calculate the electrostatic force acting on the two metal spheres. [1.56 x 10'1 N [repulsion]] 9. A metal sphere with a charge of 2.50 x 10'9 C is 1.50 cm to the left of a second metal sphere with a charge of +1.50 x 10'9 C. A third metal sphere of -1.00 x 10'9 C is situated 2.00 cm to the right of the second charged sphere. If all three charges form a line, determine the net electrostatic force on the second sphere. [1.16 x 10"!l N [left]] A H 10. From the diagram to the right determine the net .100 .ut' k ~3.0{) .uC' electrostatic force on the charge labeled C. [16.8 N at ' ' 12.6" W of S] 0.075 m H O (. 4.00 ut' 11.Two point charged objects produce an electric force of 0.0620 N on each other. What is the electric force if the distance between them increases three times and one of the charges is doubled? (0.0138 N) 12. In the diagram to the right, A has a charge of +0.30 pC, B has a charge of -0.20 [1C and C has a charge of -D.20 uC. What is the net force on A? [0.093 N [5]) . A 10cm I0 cm H. Ilium (' Electric Fields 13. Calculate the distance from an electron where the magnitude of the electric field would be 5.14 x 1011 N/C? [5.29 x 10'11 m] 14. A proton is placed in an electric field produced by another larger charge. If the magnitude of the field at this position is 1.00 x 103 MC, calculate the magnitude of the electrostatic force on the proton. [1.6 x 10'16 N] 15. An electron and a proton are 5.29 x 10'11 m apart in a hydrogen atom. Determine the net electric field at a point midway between the two charges. [4.11 x 1012 MC] [towards the electron] 16. A charge of -5.00 C is separated from another charge of -2.00 C by a distance of 1.20 m. Calculate a) The net electric field midway between the two charges [7.49 x 1010 MC [toward the -5.00 C charge]] b) The position where the net electric field is zero. [0.735 m from the -5.00 C charge] 17. Find the net electric field intensity at point C in the diagram below. [1.2 x 107 N/C [90.0]] L O 0.040 l'll 20,:C ' 2.0M: . .. .. ... .. .. .. .. .. .. .. .. .. 4. .. .. .. .. .. . . .. .. .. .. . . . A 0060 m B 18. If an alpha particle experiences an electric force of 0.250 N at a point in space, what electric force would a proton experience at the same point? [0.125 N] 19. What is the initial acceleration on an alpha particle when it is placed at a point in space where the electric field strength is 7.60 x 104 MC? [3.66 x 1012 m/sz] 20. The electric field at a position 2.00 cm from a charge if 40.0 N/C directed away from the charge. Determine the charge producing the electric field. [+1.78 x 10'12 C] 21. What is the magnitude and direction of the electric field at point Z in the diagram below? (5.8 x 105 N/C right) q = 2.0 x 10-s C 2 - 8.0 x 10 . C O 60 cm 30 cm - X Y Z 22. Determine the magnitude and direction of the electric field at location A in the diagrams below. 3 HC + 21 Q2 -4 HCC + 3 HC 1 cm 1 cm Q3 Q3 8 HC -5 uC AX -2 HC23. What is the speed of an electron that has 13.3 eV of kinetic energy? (answer: 2.16x105 m/s) 24. An alpha particle traveling 7.15x10\" m/s is accelerated [speeds up) through a potential difference with a magnitude of 15.3 V. What is the final speed of the alpha particle? (8.11x104 m/s) 25. A proton is accelerated by a potential difference of 7.20 x 102 V. What is the change in kinetic energy of the proton? [1.15 x 10'15 J] 26. An alpha particle gains 1.50 x 1015] of kinetic energy. Through what potential difference was it accelerated? [4.69 x 103 V] 27. The electric field strength between two parallel plates is 9.3 x 102 V/m when the plates are 7.0 cm apart. What would the electric field strength be if the plates were 5.0 cm apart? [1.3 x 103 Wm] 28. An electron is released from rest adjacent to the negative plate in a parallel plate apparatus. A potential difference of 500 V is maintained between the plates, and they are in a vacuum. With what speed does the electron collide with the positive plate? (1.3 x 107 m/s) 29. An electron with a velocity of 5.0 x 105 m/s is injected into a parallel plate apparatus through a hole in the positive plate. It moves across the vacuum between the plates, colliding with the negative plate at 1.0 x 105 m/s. What is the potential difference between the plates? (68 V) lmtml pall10l4- I _ hum] of clcctrunx U (Hi) m (14] (l \\' 30. Assuming that electrons enter the following parallel plate with a horizontal velocity of 3.20 x 105 m/ 5, how far will the electrons travel horizontally before they crash into the positive plate? [5.58 x 10'2 m] 31. A proton is placed in an electric field between two parallel plates. If the plates are 6.0 cm apart and have a potential difference between them of 7.5 x 10L V, how much work is done against the electric field when the proton is moved 3.0 cm parallel to the plates? [0] 32. In the previous question, how much work would be done against the electric field ifthe proton was moved 3.0 cm perpendicular to the plates? [6.0 x 1018 J]