Test 1 Solutions(07)

Test 1 Solutions(07) - PHYS 212 First Hour Exam Name...

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Unformatted text preview: PHYS 212 First Hour Exam Name February 13, 2007 , Problem Session: Hr Instr _ Show all work for full credit! Answers must have correct units and appropriate number of significant digits. For all the problems (except for multiple choice questions), start with some combination of - (a) a fundamental equation (b) a sentence explaining your approach; or (c) a sketch. 'k=8.99><109N-m2/C2 e=1.60><10'19c me=9.11><10'31k mp=1.67><10“27kg l. (15 pts) Two point charges, ql and qz are located on the x—axis at x = —3 cm and x = 3 cm, as shown in the figure. Another charge Q is located-on the y-axis at y = 4 cm. Determine the electric force on Q due to charges ql and q2. 2. (16 pts) Two large parallel conducting plates are 17 cm apart and have the electric potentials shown in the diagram. a) An electron is released from rest halfway between the plates. Determine its speed as a reaches one of the plates. EKG/SM 5} AK: /AU 5 K§_Vg :— /2_MU§Z «AV AV: b)' Which plate does it reach? 5 Pal/3’5 719 W/ mks) an am a“) 59 H’ Wfit/S 7L9 3. (.15 pts) A ZOO-loop coil with a radius of 3.0 cm is inside a long solenoid of radius 8.0 cm. The diagram shows the coil edge-on, and the coil is tilted as shown. There is a magnetic field of 1 inside the solenoid. Calculate the magnitude of the torque acting on the coil if the carries a current of 5.0 A. Plate A 2000 V ' 10,000 V 6—” E e:- . a reg Plgte lkl‘l‘lloblj 17 cm ‘ Msamv 2. IT sate. e: “fig. cab! Mam?” MW ,‘g‘lo ‘l’Lu.’ .3T coil 4. (16 pts) The figure shows a uniformly charged rod and a point P on the axis. The _ total charge on the rod is Q, with Q > 0. Determine a correct integral expression for the x-component of the electric field (Ex) at P due to the ,rod. Your expression may include only k, Q, quantities in the diagram, ' and a variable of integration. Do not evaluate the integral. 5. (10 pts) A pair of wires long, straight wires each carry current I into the page as shown. (a) The x-component of the magnetic field at point P is (circle one of the five choices below): #91 zl—f-l zl—lil 27z-(100m) 5 27Z-(10cm) 5 #91 lle Zlmlllsil [D (b) The y-component of the magnetic field at point P is (circle one of the five choices below): 2—!“ e 27: - (10cm) 5 #01 ‘ lmlgl 0 (i) 27Z-(10cm) 5 6. (8 pts) Would it be possible to suspend a proton motionless in a gravitational field using only a uniform magnetic field? If yes, explain how. If not, explain how you know it isn’t possible. 00‘ {a g V) ‘3 r r v "- m Mohawk“ ng‘ mus+=o {WQM we, flag a a fee, gmmbaohw/ gree- A 7L0 7 Q 3 a n ‘ ' ‘ [is 1))!!3 , . {I an, fiscally/‘50 A 2 F30 h‘ 77M$ 594+ :m M 74. ,0pr aweféf‘ 7. (10 pts) An electron is going through a magnetic - B Pomts out field, as shown in the diagram. In addition to the . ° ° . . magnetic field shown, there is also a uniform electric field (not shown). The electron moves in ' ° ° ° ' a straight line. @—9 — — — _ _ _ _ _ _ . _ _ a) What must be the direction of E? (Circle one) 0 O O O O _ _:> , A Q m l: ‘ % V x b D0wn Into the screen Right Out of the screen. ‘3 1-, A!) 1 S0 Felec : V Qvtd fZ/r b) A second electron enters going at twice the speed of the first. How does this second electron move through the field? (Circle one): Ubrflef V mzkes [wafet'l‘ $0 Bigger we ‘Fouf‘cg It moves in a straight line It is deflected into the page It is deflected upward It is deflected out of the page It is deflected downward There is not enough information to answer this question 8. (10 pts) A current flows in a long wire that _> makes a right-angle bend as shown in the ‘— d_.: [U 0 8 (if ,0 diagram. - P I 9 g x a) Determine the direction of the magnetic field I at a point P due to the current in the wire. G v X 19> y {ens ,{rrJLJS l b) Determine" the magnitude of the magnetic field at point P due to the current in the wire. No integrals are necessary for this. _5. Q l 9 1% P 1 fibril? 0. : /Z Blonjwhe Qt m5 wire _ I I“ / g - L No i :3 Sid _\ ,. v n a 5‘0 Bat P - /Z (fl/nine Z A( T p ...
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This note was uploaded on 04/07/2008 for the course PHYS 212 taught by Professor Ladd during the Spring '08 term at Bucknell.

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Test 1 Solutions(07) - PHYS 212 First Hour Exam Name...

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