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Name Phys212 Test I Fall 2004 For 3 7 circle the best answer 4 pts each no partial credit P 1 Two electric charges of Q and Q are arranged as shown in the figure What is the direction of the electric field at point P answer A B C D E F G H Eight coulombs of charge is spread uniformly throughout a box measuring 2m x 1m x 2m What is the 2 most appropriate charge density to describe this cube Q Q answer A 2 C m3 B 2 C m3 C 2 C m3 D 8 C E 8 C F 8 C G 32 Cm3 H 32 Cm3 I 32 Cm3 Within the volume of a conductor which of the following is true about the electric field E electric 3 potential V and charge density within the conductor answer A E 0 V 0 0 B E 0 V 0 constant C E 0 V constant 0 E E constant V 0 0 F E constant V 0 constant G E constant V constant 0 D E 0 V constant constant H E constant V constant constant Two charges are fixed in the positions shown Where could a third charge be placed so that it has no net 4 force acting on it answer region A region C center region B region D region E 2 nC 5nC A B C D E In the figure below a positive charge of Q lies at the center of an uncharged conductor Rank the 5 electric fields in each of the three locations in order of increasing E field magnitude Q I II III Consider a hollow conducting sphere which has a total charge of Q Where is the electric potential A directly at the center B between the center and the inside surface at the inside surface C D E F at the outside surface beyond the outside surface G infinitely far away from the sphere inside the conductor between the inside and outside surfaces Two charged conducting spheres of different size are attached using a thin conducting wire Compare 7 the electric potential of the two spheres answer A EI EII EIII B EI EIII EII C EII EI EIII D EII EIII EI E EIII EI EII F EIII EII EI 6 equal to zero answer A VA 4VB B VA 2VB C VA VB D VA 1 2 VB E VA 1 4 VB F Cannot be compared without knowing the amount of charge on each sphere Show your work and or explain your answers You should draw a meaningful figure for ALL problems Make sure you answer the question and use appropriate units if needed y 11pts similar to example 9 A charge is uniformly distributed along a line of length L such that the charge density is What is the 8 x component of the electric field at the point indicated below Express your answer in terms of L s and any needed constants x P L s 11pts P21 98 9 Electric charge is distributed uniformly along two sides of a square One side has a linear charge density of and the other side has a charge density of The square has sides of length w Find the x and y components of the electric field at the center of the square y Q R x A line charge of 2 nC m lies along the axis of an infinite conducting hollow cylinder shell of inner 11pts example 27 10 radius 2 cm and outer radius 3 cm A charge density of 4 nC m lies on the conducting hollow cylinder Find the electric field at a distance of 5 cm from the axis An object with a charge of 3 C and a mass of 7 g is initially located on the axis of a ring but very far 11pts similar to example 36 P23 67 11 from the center of the ring The ring is fixed in space and has a charge of 12 mC and a radius of 11 cm If the object is given n initial speed toward the center of the ring of 900 m s how close to the center of the ring will the object get

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