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Unformatted text preview: WebAssign Ch16 HW3 S2010 (Homework) Kiyaniah Tilghman PY 208, section 003M, Spring 2010 Instructor: Keith Weninger Current Score : 18.5 / 18.5 Due : Thursday, February 4, 2010 04:20 PM EST About this Assignment Extension Requests Question Points 12 3 4 2 6.5 5.5 4.5 Total 18.5/18.5 (100.0%) Description Electric field due to capacitors; electric field due to uniformly charged spheres Instructions Reading: Sec. 16.6-16.8 The due date for this assignment is past. Your work can be viewed below, but no changes can be made. 1. 2/2 points All Submissions Notes Question: MI3 16.X.055 A hollow ball of radius 6 cm, made of very thin glass, is rubbed all over with a silk cloth and acquires a negative charge of - 7.5e-08 C which is uniformly distributed all over its surface. Location A, shown in the diagram, is inside the sphere, 1 cm from the surface. Location B, shown in the diagram, is outside the sphere, 2 cm from the surface. There are no other charged objects nearby. Which of the following statements about Eball , the magnitude of the electric field due to the ball, are correct? Select all that apply. At location B Eball is 1.69 106 N/C. A hydrogen atom at location A would polarize because it is close to the negative charges on the surface of the sphere. At location A Eball is 0 N/C. All of the charges on the surface of the sphere contribute to Eball at location A. 2. 6.5/6.5 points All Submissions Notes Question: MI3 16.P.064 A small, thin, hollow spherical glass shell of radius R carries a uniformly distributed positive charge + Q , as shown in the diagram above. Below it is a horizontal permanent dipole with charges + q and - q separated by a distance s ( s is shown greatly enlarged for clarity). The dipole is fixed in position and is not free to rotate. The distance from the center of the glass shell to the center of the dipole is L. The charge on the thin glass shell is +5e-09 coulombs, the dipole consists of charges of 4e-11 and - 4e-11 coulombs, the radius of the glass shell is 0.12 m, the distance L is 0.36 m, and the dipole separation is 2e-05 m. Calculate the net electric field at the center of the glass shell. The x axis runs to the right, the y axis runs toward the top of the page, and the z axis runs out of the page, toward you. = < 1.54e-4 0.000154 , 0 0 ,0 0 > N/C If the upper sphere were a solid metal ball with a charge +5e-09 coulombs, what would be the net electric field at its center? =< 0 0 ,0 0 ,0 0 > N/C Which of the diagrams below best shows the charge distribution in and/or on the metal sphere? E E A B C D E F G H J K 3. 5.5/5.5 points All Submissions Notes Question: MI3 16.X.053 A solid metal ball of radius 1.2 cm bearing a charge of - 15 nC is located near a hollow plastic ball of radius 1.7 cm bearing a uniformly distributed charge of -4 nC (see the figure) on its outer surface. The distance between the centers of the balls is 9 cm. Assume the + x axis runs to the right, the +y axis runs up and the +z axis is out. What is the electric field at the center of the metal ball due only to the charges on the plastic ball? = < 4.4e3 4440 , 0 0 ,0 0 > N/C What is the net electric field at the center of the metal ball? =< 0 0 ,0 0 ,0 0 > N/C What is the electric field at the center of the metal ball due only to the charges on the surface of the metal ball? = < -4.4e3 - 4440 , 0 0 ,0 0 > N/C 4. 4.5/4.5 points All Submissions Notes Question: MI3 16.P.042.alt01 In a cathode-ray tube (CRT), an electron travels in a vacuum and enters a region between two "deflection" plates which have equal and opposite charges. The dimensions of each plate are L = 12 cm by d = 5 cm, and the gap between them is h = 2.5 mm (not to scale in the diagram). During a 0.001 s interval while it is between the plates, the change of the momentum of the electron ! is < 0, - 4.80e-17, 0 > kg m/s. What is the electric field between the plates? Hint: remember the Momentum Principle (the relationship between Impulse and change in momentum.) =< 0 0 , 300000 3.00e+05 , 0 0 > N/C =< 0 , 300000 ,0 > N/C What is the charge (both magnitude and sign) of the upper plate? q = - 1.593e-8 - 1.59e-08 C ...
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