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PHYS 2212-Sections P and Q, Test 1, February 5,20Name (print)CIRCLE ONE: SECTION P (Gole) SECTION Q (Goldman)Instructions Read all problems carefully before attempting to solve them. Your work must be legible, and the organization must be clear. You must show all work, Including correct vector notation. Correct answers without adequate explanation will be counted wrong. Incorrect work or explanations mixed In with correct work will be counted wrong. Cross out anythingyou don't want us to readl Make explanations correct but brief. Don't write a lot of prose. Include dlagramsl

ab (8x 10-3)(5 x 106 ) Show what goes Into a calculation, not Just the final number, e.g.: - - 5 4 - 5X 104cd (2xlO- )(4x10 ) Give standard SI units with your results.Unless specifically asked to derive a reSUlt, you may start from the formulas given on the formula sheet,Including equations corresponding to the fundamental concepts. If a formula you need Is not given, youmust derive It.If you cannot do some portion of a problem, Invent a symbol for the quantity you can't calculate (explainthat you are doing this), and use It to do the rest of the problem.

Honor pledge' 'In accordance with the Georgia Tech Honor Code, I have neither given nor received unauthorized aid on this test."

Sign your name on the line above

PROB.l _PROB.2 _PROB.3. _

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Problem 1 (32 pts)A point charge of -15 nC (-15 x 10-9 C) is located at < 4, 3, -2> m. A second point charge of +7 nC is located at < 3, -5, 1>m.

(a, 12 pts) What is the (vector) electric field contributed by the -15 nC charge at observation location < 6, 2, 3> m? You needto show all your work carefully in order to get credit.r:: ~ L _ - =- 4.S'0 (0.'31,-0.1', O.c;,>'+11 fo I ~ , S"'18)"

(b, 12 pts) What is the (vector) electric field contr ibuted by the +7 nC charge at observation location < 6,2, 3> m? You needto show all your work carefully in order to get credit.

- ' t_ . . . : , r - r O ~ 1 - '-StJtlt",c, : ' < ~ , 1 , 3 '> -

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Problem 2 (32 pts)(a, 8 pts) Location A is the same distance' from the centers of two dipoles, as shown inthe diagram. Dipoles I and 2 consist of the same charges, +q and -q, separated by the dipole I ~ + same distance s. At location A on the diagram, draw the electric field vector due todipole I and the electric field vector due to dipole 2. Label the vectors E 1 and E2, G-q Trespectively. A longer arrow should represent a field with larger magnitude. I II ,

I I '(b, 10 pts) The distance' = 3e-1O m. The magnitude of the charge of one end of eachdipole q =1.6e-19 C. The separation between the two charges s=2.8e-14 m. Calculate J71he electric field at location A. Express your answer as a three-component vector.

~ : :I II III I"

;;. ((, (, '/0 -/1) ( 1. 9 ,/0 . ' ' ' ) II IIdipole2 1

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Problem 3 (36 pts)Two identical pieces of invisible tape are stuck together, one on top the other. The upper tape we'l l call the V-tape, the lowerone the L-tape. You rub the slick side of the two-tape system until it is no longer attracted to your hand. You then rip themapart. You find a negatively charged plastic pen repels the L-tape. You then move the two tapes apart as shown in thediagram.(a, 8 pts) At the location marked with an "x", draw arrows representing the electric field due to the V-tape and the electricfield due to the L-tape. Label the arrows Eu and EL respectively. If either is zero, say so explicitly. A longer arrow shouldrepresent a field with larger magnitude.

V-tape L-tape(b, 8 pts) Next you place a neutral plastic block between the tapes as shown below. On the diagram, draw the following: Any polarization or charge distribution in or on the plastic block, using the diagram convention used in the book and in

class. The electric field due to the plastic block alone at the location marked "x". Label it Eplastic' If it is zero, say so explicitly., . . .- r-

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