Name: Lab Day/Time: Monday Homework 3 Electric Maps and Gauss Multiple Choice Problems The questions in this section are to be answered by circling the correct multiple-choice answer AND providing a short justification of your answer in the space after the problem.. Monday Homework Problem 3.1 A hula hoop of radius 1.0m is in a uniform electric field with magnitude 1.0 × 102 N C . Its normal is perpendicular to the field (careful here). What is the flux through the hoop? Select One of the Following: 2 (a) 310 N Cm 2 (b) 620 N Cm 2 (c) 1.0 × 102 N Cm (d) 0 Monday Homework Problem 3.2 A hula hoop of radius 1.0m is in a uniform electric field with magnitude 1.0 × 102 N C . Its normal is parallel to the field (careful here). What is the flux through the hoop? Select One of the Following: 2 (a) 310 N Cm 2 (b) 620 N Cm 2 (c) 1.0 × 102 N Cm (d) 0 Monday Homework Problem 3.3 A field map is shown to the right, the dashed region contains a distribution of charge. Select one of the following that best describes the distribution of charge. Select One of the Following: (a) monopole system, positive net charge (b) monopole system, negative net charge (c) dipole system, dipole moment toward the left of page (d) dipole system, dipole moment toward the right of page (e) dipole system, dipole moment toward the top of page (f) dipole system, dipole moment toward the bottom of page 1 Monday Homework Problem 3.4 A golf tube has total charge −0.1µC. Compute the total electric flux out of the lab room containing the charged golf tube and no other net charge. Select One of the Following: (a) This cannot be solved because the room is not spherical. (b) 0 (c) −7 × 105 Nm2 /C (d) −1 × 104 Nm2 /C (e) This cannot be calculated because the distance from the charge to the walls of the room is not given. Monday Homework Problem 3.5 A spherical balloon has a surface charge density of σ on its outer surface and has radius a. What is the electric field outside the balloon at all points in space? Select One of the Following: (a) (b) (c) (d) (e) σ r̂ ε0 aσ r̂ ε0 r a2 σ r̂ ε0 r 2 σ r̂ 4πε0 r2 0 Monday Homework Problem 3.6 The world’s largest Van de Graaff generator produces an electric field of 4.4 × 105 N C at its surface using an electrode that is a sphere of radius 4.5m. How much total charge must be on the surface of the sphere to produce this field? Select One of the Following: (a) 2.2 × 10−4 C (b) 9.9 × 10−4 C (c) 4.5 × 10−3 C (d) 3.2 × 10−2 C (e) 1.1 × 10−1 C 2 Monday Homework Problem 3.7 Select the statement that describes motion of an electric dipole placed in an electric field. Select One of the Following: (a) The dipole is unaffected by the field. (b) The dipole will be attracted to the field. (c) The dipole will be repelled by the field. (d) The dipole will rotate until its moment points in the same direction as the field. (e) The dipole will rotate until its moment points in the opposite direction to the field. Monday Homework Problem 3.8 The diagram to the right shows the electric field lines for some charge distribution. The electric force vectors are drawn for a proton placed at points A through E. Only one of the vectors is correctly drawn. Which vector is correctly drawn? A B C E D Select One of the Following: (a) The vector at point A is correctly drawn. (b) The vector at point B is correctly drawn. (c) The vector at point C is correctly drawn. (d) The vector at point D is correctly drawn. (e) The vector at point E is correctly drawn. 3 Monday Homework Problem 3.9 The spacing of the electric field lines at point A is much smaller than the spacing at point B. What is the relation of the electric force exerted on a +q charge placed at point A or point B? Select One of the Following: (a) The force exerted on the charge at point A is much larger than the force exerted on the charge at point B. (b) The force exerted on the charge at point A is much smaller than the force exerted on the charge at point B. (c) The force exerted on the charge at point A equal to the force exerted on the charge at point B. Monday Homework Problem 3.10 A positively charged particle is released at point A in the electric field drawn to the right. Which of the following best describes the particle’s trajectory? Select One of the Following: (a) The particle’s trajectory will follow the field line. (b) The particle will initially move in the direction of the field line, but the trajectory will not necessarily follow the field line. 4 A