# HW 18 - benavides(jjb2356 homework 18 Turner(59130 This...

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benavides (jjb2356) – homework 18 – Turner – (59130) 1 This print-out should have 9 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points An air-flled cylindrical capacitor has a capac- itance oF 8 p± and is 4 cm in length. The coulomb constant is 8 . 98755 × 10 9 N · m 2 / C 2 . IF the radius oF the outside conductor is 2 . 4 cm, what is the required radius oF the inner conductor? Correct answer: 1 . 81722 cm. Explanation: Let : k e = 8 . 98755 × 10 9 N · m 2 / C 2 , = 4 cm = 0 . 04 m , b = 2 . 4 cm , and C = 8 p± = 8 × 10 12 ± . The capacitance oF a cylindrical capacitor is given by C = 2 k e ln b a where a and b are the inner and outer radii, respectively. Solving For a , we obtain a = b e ℓ/ (2 k e C ) = (2 . 4 cm) e (0 . 04 m) / [2 k e (8 × 10 - 12 F)] = 1 . 81722 cm . 002 10.0 points IF the plate separation oF an isolated parallel plate capacitor is doubled, 1. the charge density on each plate is dou- bled. 2. None oF these correct 3. the charge on the each plate is halved. 4. the electric feld is doubled. 5. the potential di²erence is halved. Explanation: Q and A are constant, so E = Q A ǫ 0 = constant so that E = 2 Q 2 A ǫ 0 and V = Q C = 2 Q C = 2 Q C = 2 V . 003 (part 1 oF 2) 10.0 points Consider the system oF capacitors connected to a battery as shown below. E B 3 μ ± 3 μ ± 3 μ ± 3 μ ± 3 μ ± 3 μ ± ±ind the equivalent capacitance oF the cir- cuit. 1. C = 2 3 μ ± 2. C = 1 μ ± 3. C = 2 μ ± correct 4. C = 3 2 μ ± 5. C = 4 3 μ ± 6. C = 3 μ ± 7. C = 4 μ ± Explanation:

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HW 18 - benavides(jjb2356 homework 18 Turner(59130 This...

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