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Name: Lab Day/Time: Monday Homework 2 Electrostatics Monday homework is due at the beginning of the Monday lecture. It must be handwritten, not typeset. The multiple-choice answers must be circled. In the space after the problem, a short justification of the answer is must be included. You will lose 2 points if the assignment is not stapled, if you do not write the lab day/time on the assignment, or if the assignment is turned into the wrong section folder. 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 2.1 The two protons in the helium nucleus are about 1 × 10 - 15 m apart. What is the magnitude of the electric force one proton exerts on the other? Select One of the Following: (a) 200N (b) 1 × 10 - 20 N (c) 5 × 10 - 1 N (d) 4 × 10 - 6 N (e) 3 × 10 9 N Monday Homework Problem 2.2 A point charge q with charge q =4 . 0nC is at the point vector r 0 =( - 4 . 0cm , 4 . 0cm , 0) . Calculate the electric field at the point vector r P =( - 8 . 0cm , 12 . 0cm , 0) . Select One of the Following: (a) 4495 N C (0 . 45 , - 0 . 89 , 0) (b) 4495 N C (0 . 57 , - 0 . 82 , 0) (c) 2158 N C (0 . 57 , - 0 . 82 , 0) (d) 4495 N C ( - 0 . 45 , 0 . 89 , 0) (e) 3709 N C ( - 0 . 71 , 0 . 71 , 0) (f) 2250 N C ( - 0 . 45 , 0 . 89 , 0) (g) 2250 N C (0 . 45 , 0 . 89 , 0) 1

Monday Homework Problem 2.3 A point charge q with charge q =4 . 0nC is at the point vector r 0 =( - 4 . 0cm , 4 . 0cm , 0) . Calculate the electric field at the point vector r P =( - 8 . 0cm , 12 . 0cm , 0) . Select One of the Following: (a) 4495 N C (0 . 45 , - 0 . 89 , 0) (b) 4495 N C (0 . 57 , - 0 . 82 , 0) (c) 2158 N C (0 . 57 , - 0 . 82 , 0) (d) 4495 N C ( - 0 . 45 , 0 . 89 , 0) (e) 3709 N C ( - 0 . 71 , 0 . 71 , 0) (f) 2250 N C ( - 0 . 45 , 0 . 89 , 0) (g) 2250 N C (0 . 45 , 0 . 89 , 0) Monday Homework Problem 2.4 If DNA has a charge of 0 . 3 e per base pair in solution and there are 3 × 10 9 base pairs in a human genome, then the total charge of the human genome in solution is 1 . 4 × 10 - 10 C . If the DNA molecule is placed in an electric field of 100 , 000 N C , what would the acceleration of the DNA molecule be? The mass of a DNA molecule is on the order of 3 × 10 - 15 kg . Select One of the Following: (a) 2 m s 2 (b) 3 × 10 3m s 2 (c) 0 . 1 m s 2 (d) 5 × 10 9m s 2 (e) 4 × 10 - 20m s 2 Monday Homework Problem 2.5 Suppose you want to float a truck with a mass of 10 , 000kg in earth’s gravity by placing a charge of 3C on the truck and floating it above an infinite plane with surface charge density σ . What must σ be? Select One of the Following: (a) 5 . 8 × 10 - 7 C / m 2 (b) 1 . 7 × 10 - 5 C / m 2 (c) 3 . 4 × 10 - 5 C / m 2 (d) 3 . 0 × 10 - 3 C / m 2 (e) 2 . 1 × 10 - 2 C / m 2 2

Monday Homework Problem 2.8 Lightning strikes the power lines, briefly transferring a linear charge density of 1 . 0 × 10 - 3 C m . Model the power lines as a single infinite straight uniform line charge. Calculate the magnitude of the electric field at the ground a distance of 5 . 0m from the wire. Select One of the Following: (a) 3 . 6 × 10 5N C (b) 1 . 8 × 10 6N C (c) 3 . 6 × 10 6N C (d) 7 . 2 × 10 5N C (e) 3 . 5 × 10 8N C Monday Homework Problem 2.9 A pith ball with charge +1 . 5nC is fixed at the origin. A second +1 . 5nC pith ball floats vertically above the first. Modelling both pith balls as point charges, compute the center-to-center separation of the two pith balls. The mass of a pith ball is 6 . 0 × 10 - 5 kg . Note, the distance calculated may or may not be larger than the radius of the pith ball. Select One of the Following: (a) 5 . 9 × 10 - 3 m (b) 3 . 4 × 10 - 5 m (c) 6 . 3 × 10 - 1 m (d) 1 . 3m (e) 150m 4

Monday Homework Problem 2.10 A positively charged rod is brought near to, but does not touch, the outer surface of a neutral, hollow, metal conductor as shown below. Which of the following figures best describes the surface charge densities induced on inner and outer surface of the conductor? Select One of the Following: (a) Figure (a) (b) Figure (b) (c) Figure (c) (d) Figure (d) (e) Figure (e) + conductor air + _ _ + + _ + + _ _ _ + + Figure (e) Figure (a) Figure (b) Figure (c) Figure (d) + _ _ _ _ _ _ + + + + + + _ _ + + _ + + _ _ _ + + + + + + + _ _ _ _ _ _ _ + + _ + + _ _ _ + + + + _ _ + + _ + + _ _ _ + + + + + + + _ _ _ _ _ 5