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Unformatted text preview: Create assignment, 99552, Homework 18, Apr 01 at 8:48 pm 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. Charge in a Nickel 23:01, trigonometry, numeric, > 1 min, nor- mal. 001 We want to find how much charge is on the electrons in a nickel coin. Follow this method. A nickel coin has a mass of about 5 g. Each mole (6 . 02 10 23 atoms) has a mass of about 58 g. Find the number of atoms in a nickel coin. Correct answer: 5 . 18966 10 22 atoms. Explanation: Let : N a = 6 . 02 10 23 atoms , M = 58 g , and m = 5 g . Mass is proportional to the number of atoms in a substance, so for m grams in N atoms in the nickel coin and M grams in N a atoms in one mole, we have m M = N N a N = m M N a = (5 g) (58 g) (6 . 02 10 23 atoms) = 5 . 18966 10 22 atoms . 002 Find the number of electrons in the coin. Each nickel atom has 28 electrons / atom. Correct answer: 1 . 4531 10 24 electrons. Explanation: Let : n Ni = 28 electrons / atom . If n Ni electrons are in each Nickel atom, then the total number of electrons n e in the coin is n e = N n Ni = ( 5 . 18966 10 22 atoms ) (28 electrons / atom) = 1 . 4531 10 24 electrons . 003 Find the magnitude of the charge of all these electrons. Correct answer: 232813 C. Explanation: Let : q e =- 1 . 60218 10- 19 C / electron . The total charge q for the n e electrons is q = n e q e = (1 . 4531 10 24 electrons) (- 1 . 60218 10- 19 C / electron ) =- 232813 C , which has a magnitude of 232813 C . keywords: Charge in Lightning 03 23:01, trigonometry, numeric, > 1 min, nor- mal. 004 A strong lightning bolt transfers about 25 C to Earth. The charge on an electron is 1 . 60218 10- 19 C. How many electrons are transferred? Correct answer: 1 . 56038 10 20 . Explanation: Let : q = 25 C . The charge is proportional to the number of electrons, so q = nq e n = q q e =- 25 C- 1 . 60218 10- 19 C = 1 . 56038 10 20 . Create assignment, 99552, Homework 18, Apr 01 at 8:48 pm 2 keywords: AP EM 1998 MC 39 40 23:05, trigonometry, numeric, > 1 min, wording-variable. 005 Two charged particles of equal magnitude (+ Q and- Q ) are fixed at opposite corners of a square that lies in a plane (see figure be- low). A test charge- q is placed at a third corner. + Q- q- Q What is the direction of the force on the test charge due to the two other charges? 1. correct 2. 3. 4. 5. 6. 7. 8. Explanation: The force between charges of the same sign is repulsive. The force between charges with opposite signs is attractive. + Q- q- Q The resultant force is the sum of the two vectors in the figure above. Therefore the correct choice is 006 If F is the magnitude of the force on the test charge due to only one of the other charges, what is the magnitude of the net force act- ing on the test charge due to both of these charges?...
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