# HW 5 - Kapoor(mk9499 homework05 Turner(60230 This print-out...

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Kapoor (mk9499) – homework05 – Turner – (60230) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 (part 1 oF 2) 10.0 points A charged mass on the end oF a light string is attached to a point on a uniFormly charged vertical sheet oF infnite extent. The acceleration oF gravity is 9 . 8 m / s 2 and the permittivity oF Free space is 8 . 854 × 10 12 C 2 / N · m 2 . 43 . 2 cm θ ˆ ı ˆ 0 . 33 μ C 1 g Areal charge density 0 12 μ C / m 2 ±ind the angle θ the thread makes with the vertically charge sheet. Correct answer: 12 . 8543 . Explanation: Let : g = 9 . 8 m / s 2 , ǫ 0 = 8 . 854 × 10 12 C 2 / N · m 2 , m = 1 g = 0 . 001 kg , σ = 0 . 12 μ C / m 2 = 1 . 2 × 10 7 C / m 2 , q = 0 . 33 μ C = 3 . 3 × 10 7 C , and L = 43 . 2 cm = 0 . 432 m . The length L oF the string is super²uous. Let the tension in the string be denoted by T . The electric feld due to the infnite sheet is constant in the x -direction and is v E = σ 2 ǫ 0 ˆ ı . In the ˆ ı and ˆ directions, Force equilibrium tells us T sin θ = q · σ 2 ǫ 0 T cos θ = m g tan θ = T sin θ T cos θ = q σ 2 m g ǫ 0 θ = arctan p q σ 2 m g ǫ 0 P = arctan b (3 . 3 × 10 7 C) (1 . 2 × 10 7 C / m 2 ) 2 (0 . 001 kg) (9 . 8 m / s 2 ) ǫ 0 B = 12 . 8543 . 002 (part 2 oF 2) 10.0 points What value would σ in order For he angle 76 ? Correct answer: 2 . 10917 μ C / m 2 . Explanation: ±rom the previous part, we know σ = 2 m g tan θ q ǫ 0 = 2 (0 . 001 kg) ( 9 . 8 m / s 2 ) tan(76 ) 3 . 3 × 10 7 C · (8 . 854 × 10 12 C 2 / N · m 2 ) 10 6 μ C 1 C = 2 . 10917 μ C / m 2 . 003 10.0 points A net positive charge Q is placed on a large, thin conducting plate oF are A . In electrostatic equilibrium the charge den- sity σ on each surFace and the electric feld E outside the plate are 1. σ = Q A , E = σ ǫ 0 2. σ = Q 2 A , E = 0 3. σ = Q 2 A , E = σ ǫ 0 correct 4. σ = Q 2 A , E = σ 2 ǫ 0 5. σ = 0 , E = σ ǫ 0

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Kapoor (mk9499) – homework05 – Turner – (60230) 2 Explanation: 004 10.0 points A nonconducting plate with infnite dimen- sions carries a uniForm surFace charge density oF 11 . 72 μ C / cm 2 . What is the electric feld 5 . 2 cm in Front oF the plate?
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HW 5 - Kapoor(mk9499 homework05 Turner(60230 This print-out...

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