r 2 and the charge on a proton is +e. We never see objects that have a charge which is not a whole number multiple of this number.

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1 Name: Physics Chapter 16 Study Guide Useful Information: e = 1.6"10 #19 C mass electron = 9.11"10 #31 kg mass proton =1.67 "10 #27 kg k = 9 "10 9 Nm 2 F = kq 1q 2 C 2 r 2 F = Eq E = kq r A Basic Understanding: Chapter 16 Odd Numbered Core Problems Chapter 16 Review Problems:! 3, 5, 7, 16, 18, 21, 32, 35, 38, 41. Pushing to be Better: Chapter 16 You Try Problems Chapter 16 Even Numbered Core Problems Chapter 16 Review Problems: 1, 6, 9, 10, 14, 17, 19, 20, 24, 31, 33, 36, 40, 43, 44, 45, 47, 48, 50, Standardized Test Prep Digging Deeper: Chapter 16 Review Problems: 2, 4, 15, 30, 37, 42, 46, 49, 52, 54, 55. Individual Inquiry Notes on Chapter 16 Equations: e = 1.6"10 #19 C This is the fundamental unit of charge. The charge on an electron is -e and the charge on a proton is +e. We never see objects that have a charge which is not a whole number multiple of this number. k = 9 "10 9 Nm 2 2 This is Coulomb s Constant. It is a fudge factor necessary to make C the next equation down give force units in Newtons when the charges are in Coulombs and the distance between the charges is in meters. F = kq 1q 2 r 2 This is the equation for the force between two charged particles. k is given above. q1 and q2 are the two charges, as measured in Coulombs. You should not think of r as a radius in these equations. You should think about it as the center to center distance between two charged particles. F = Eq This equation relates the concepts of Electric Field and Electric Force and charge. Sometimes we do not know where or how many charges there are that are causing an electric field. But, we can measure the electric field, and determine the force it would have on a charge. Physics Ch.16 Study Guide page 1 of 4

2 E = kq See above. If you take F = Eq and solve it for E you take the first equation r 2 and remove one of the q s. Physics Ch.16 Study Guide page 2 of 4

3 Worked Example #1: Four electric charges of +2.5 nc are placed at the corners of a square with a side length of 10cm. Calculate the electric force on one of the charges. Your Try: Three point charges each with a magnitude of -5.9 µc are placed at the corners of a 3cm-4cm-5cm right triangle. Calculate the electric force on the charge placed at the right-angle of this triangle. Physics Ch.16 Study Guide page 3 of 4

4 Worked Example #2: An aluminum ball has a mass of 0.35 grams. It hangs from a light thread in a horizontal electric field of 732 N/C. The thread makes an angle of 8.20 with the vertical. Calculate the charge on the aluminum ball. Your Try: A small ball has a mass of 0.13 grams and a charge of 9.83 µc. It is hung from a light thread in an electric field of unknown strength. The thread makes an angle of What is the electric field strength. Physics Ch.16 Study Guide page 4 of 4

5 Physics Chapter 16 Your Try Problems (Based on various worked examples.) 3) Video 16j: A proton is placed in an electric field of 130 N/C. a) What is the force on the proton? b) What is the kinetic energy of the proton after it moves 1.0 mm? c) What is the speed of the proton after it moves 1.0 mm? d) What is the momentum of the proton after it moves for 1.0 ms? e) What is the speed of the proton after it moves for 1.0 ms? 4) Video 16L: A charge of 1.4 mc is placed 13cm from a charge of 2.7 mc. Determine a location where the Electric Field is zero.

6 Answers to Chapter 16 Your Try Problems Worked Example #1: Three point charges each with a magnitude of F = 400 N at an angle of 29 off of the 3cm side of the triangle. Worked Example #2: A small ball has a mass of 0.13 grams and a charge of... E = 30 N/C. 3) Video 16j: A proton is placed in an electric field of 130 N/C... a) 2.08E-17 N b) 2.08E-20 J c) 5000 m/s d) 2.08E-20 kg m/s e) You come up with 1.25E7 m/s using the normal equations. But, you really need to use the relativistic equations since you re so close to the speed of light. 4) Video 16L: A charge of 1.4 mc is placed 13cm from a charge of 2.7 mc cm from the 1.4 mc charge.

7 Name: Physics Chapter 16 Core Problems 1) An electron and a proton are placed in the same electric field. True or False. T/F They will both accelerate at the same rate. T/F They will travel in opposite directions. T/F They will have the same kinetic energy after a short time t has elapsed. T/F They will have the same momentum after a short time has elapsed. T/F They will be subject to the same force. T/F They will have the same kinetic energy after travelling a short distance d. T/F They will have the same momentum after travelling a short distance d. 2) A charge of nc is placed on a conducting sphere with a radius of 12.3 cm. The electric field inside the sphere: a) 23.3 m/c. b) depends on your location within the sphere. c) C/m. d) cannot be determined from the information given. e) 0 N/C. 3) A negatively charged object is brought close to the surface of a conductor, whose opposite side is then grounded. The charge left on the conductor s surface is: a) neutral b) positive c) both positive and negative d) half that of the negatively charged object. e) negative 4) Find the electric field at a point midway between two charges of nc and nc separated by a distance of 30.0 cm. 5) Calculate the force between a point charge of µc and a point charge of µc that are separated by a distance of 17.8 cm. State whether the force is attractive or repulsive. Physics Ch. 16 Core Problems page 1 of 2

8 6) Four point charges are arranged at the corners of a square as shown in the diagram below. Calculate the value of Q 4 that will make the net force on Q 2 equal to zero Newtons. (This problem does, in fact, have a solution.) Q 2 = +8.9µC Q 3 = 2.3µC 10cm Q 1 = 2.3µC 10cm Q 4 =? 7) A small ball has a mass of 0.69 grams and a charge of 2.11 mc is hung from a light thread in an electric field of 823 N/C. What angle does the thread make with the vertical. 8) A charge of +2.8 nc is placed 0.65 meters from a second charge of +0.5 nc. A third charge has a charge of -1.0 nc. Where should you place the third charge so that the net force on the third charge is 0.00 Newtons? Physics Ch. 16 Core Problems page 2 of 2

and the charge on a proton is +e. We never see objects that have a charge which is not a whole number multiple of this number.

and the charge on a proton is +e. We never see objects that have a charge which is not a whole number multiple of this number. Name: Physics Chapter 17 Study Guide ----------------------------------------------------------------------------------------------------- Useful Information: e = 1.6"10 #19 C k = 9 "10 9 Nm 2 C 2 $ 0