2. E A 3. E A 4. E A 5. E A

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1 west (mrw3223) HW 23 lyle (16001) 1 This print-out should have 32 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. Reading assignment: Hecht Sections 15-3 and points A positive test charge of C is placed in an electric field of N/C intensity. Whatisthestrengthoftheforceexertedon the test charge? points A test charge has a force of N on it when it is placed in an electric field intensity of N/C. What is the magnitude of the charge? Answer in units of C points A positive charge of C experiences a force of N when located at a certain point. What is the electric field magnitude at that point? points A proton and an electron in a hydrogen atom are separated on the average by about m. What is the magnitude of the electric field set up by the proton at the location of the electron? The value of the Coulomb constant is N m 2 /C points The diagram shows an isolated, positive charge Q, where point B is twice as far away from Q as point A. Q A B 0 10 cm 20 cm What is the ratio of the electric field strength at point A to the electric field strength at point B? 1. E A = E A = E A = E A = E A = (part 1 of 2) 10.0 points Two charges are located on a horizontal axis. p 1.8 µc 1.6 m 1.8 µc Determine the electric field at p on a vertical axis as shown in the figure, where up is positive. The Coulomb constant is Answer in units of V/m. 007 (part 2 of 2) 10.0 points Find the vertical component of the electric force on a 4 µc charge placed at point p points Two charges are located in the (x,y) plane as shown. The fields produced by these charges are observed at a point p with coordinates (0,0). 7.2 C 3 m 1.8 m p 1.5 m 7.9 C Find the x-component of the electric field

2 west (mrw3223) HW 23 lyle (16001) 2 at p. The value of the Coulomb constant is points Fromtheelectricfieldvectoratonepoint,one can determine which of the following? A. The magnitude of the electrostatic force exerted per unit charge on a test charge at that point. B. The electrostatic charge at that point. C. The direction of the electrostatic force on a test charge of known sign at that point. 1. B only 2. All are true. 3. A, B, and C 4. B and C only 5. A and C only 6. A only 7. None is true. 8. C only 9. A and B only 010 (part 1 of 2) 10.0 points Two positive charges of 5.28 µc each are 334 cm apart. Find the electric field midway between them. The value of the Coulomb constant is 1. E = N/C 2. E = N/C 3. E = N/C 4. E = 0 N/C 6. E = N/C 7. E = N/C 8. E = N/C 9. E = N/C 10. E = N/C 011 (part 2 of 2) 10.0 points What is the magnitude of the electric field if one charge is positive and the other negative, both of magnitude 5.28 µc? 1. E = N/C 2. E = N/C 3. E = N/C 4. E = N/C 5. E = 0 N/C 6. E = N/C 7. E = N/C 8. E = N/C 9. E = N/C 10. E = N/C points A charge of 4.36 µc is located at the origin, and a charge of 4.15 µc is located along the y axis at m. Atwhatpointalongthey-axisistheelectric field zero? The value of the Coulomb constant is N m 2 /C 2. Answer in units of m. 013 (part 1 of 2) 10.0 points Consider three charges arranged as shown. 5. E = N/C

3 west (mrw3223) HW 23 lyle (16001) µc 1.8 µc 3.7 µc 4.1 cm 1.6 cm What is the magnitude of the electric field strength at a point 2.9 cm to the left of the middle charge? The value of the Coulomb constant is What is the direction of this electric field (as an angle measured from the positive x- axis, within limits of 180 to 180, with counterclockwise positive)? Answer in units of points Three identical charges are along a circle of radius of 8.3 m at angles of 54, 174, and 294, as shown. 014 (part 2 of 2) 10.0 points What is the magnitude of the force on a 3.7 µc charge placed at this point? (part 1 of 2) 10.0 points An electron is accelerated by a constant electric field of magnitude 300 N/C. Find the magnitude of the acceleration of the electron. The mass of an electron is kg and the elemental charge is C. Answer in units of m/s (part 2 of 2) 10.0 points Find the electron s speed after s, assuming it starts from rest. 017 (part 1 of 2) 10.0 points Three positive charges are arranged as shown at the corners of a rectangle nc 7.46 nc 0.33 m 0.11 m 2.54 nc Find the magnitude of the electric field at the fourth corner of the rectangle. The value of the Coulomb constant is 018 (part 2 of 2) 10.0 points What is the resultant electric field at the center of the circle? The Coulomb constant is N m 2 /C points Three point charges are placed at the vertices of an equilateral triangle. 1.4 C m 1.4 C P 1.4 C Find the magnitude of the electric field vector E at P. The value of the Coulomb constant is N m 2 /C (part 1 of 2) 10.0 points The electric field near the surface of the earth points downward and has a magnitude of 190 N/C. Compare the upward electric force on an electron with the downward gravitational ĵ î

4 west (mrw3223) HW 23 lyle (16001) 4 force; i.e., what is the ratio F e F g? The elementarycharge is C andthemass of an electron is kg. 022 (part 2 of 2) 10.0 points What is the magnitude of the charge that should be placed on a coin of mass 6.7 g so that the electric force balances the weight of the coin near the earth s surface? Answer in units of C points An object having a net charge of 37.8 µc is placed in a uniform electric field of 527 N/C directed vertically up. What isthemassofthisobject ifit floats in the field? The acceleration due to gravity is 9.8 m/s 2. Answer in units of g. 024 (part 1 of 2) 10.0 points A small 1.3 g plastic ball is suspended by a 30.4 cm long string at an angle of 42.9 in a uniform electric field of 3930 N/C, as shown N/C due to gravity is 9.8 m/s 2, and the Coulomb constant is Answer in units of µc. 026 (part 1 of 2) 10.0 points An electron and a proton are each placed at rest in an electric field of 356 N/C. What is the velocity of the electron 70.9 ns after being released? Consider the direction parallel to the field to be positive. The fundamental charge is C and the mass of an electron is kg. 027 (part 2 of 2) 10.0 points What is the velocity of the proton 70.9 ns after being released? The mass of the proton is kg. 028 (part 1 of 3) 10.0 points An electron traveling at m/s enters a 0.06 m region with a uniform electric field of 282 N/C, as in the figure m ĵ m/s î 30.4 cm 1.3 g Is the ball s charge positive or negative? 1. Positive 2. Negative 3. Unable to determine 025 (part 2 of 2) 10.0 points If the ball is in equilibrium when the string makes a 42.9 angle with the vertical, what is the net charge on the ball? The acceleration Find the magnitude of the acceleration of the electron while in the electric field. The mass of an electron is kg and the fundamental charge is C. Answer in units of m/s (part 2 of 3) 10.0 points Find the time it takes the electron to travel through the region of the electric field, assuming it doesn t hit the side walls. Answer in units of s. 030 (part 3 of 3) 10.0 points What is the magnitude of the vertical displacement y of the electron while it is inthe electric field? Answer in units of m.

5 west (mrw3223) HW 23 lyle (16001) points The electron gun in a television tube is used to accelerate electrons with mass kg from rest to m/s within a distance of 4.6 cm. Assuming the electric field is constant, what electric field is required in the tube? The fundamental charge is q e points A small electrically charged object is suspended by a thread between the vertical plates of a parallel-plate capacitor. 5.4 cm θ=23 θ A 426 mg 31 nc B E E What is the potential difference between the plates? The acceleration of gravity is 9.8 m/s 2. Answer in units of kv.