UnitExam5Asolutions

UnitExam5Asolutions - ID: A UCSD Physics 2B Answer Section...

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ID: A 1 UCSD Physics 2B Unit Exam 5A AC Circuits Answer Section MULTIPLE CHOICE 1. ANS: D Vt () = V P sin ω t V P = sin t = 122 V sin 314 rad / s 0.153 s Ï Ì Ó Ô Ô Ô ¸ ˝ ˛ Ô Ô Ô = 154 V TOP: AC VOLTAGE 2. ANS: A Flux through a solenoid Φ= NBA = N μ 0 I N length Ê Ë Á Á Á Á Á Á ˆ ¯ ˜ ˜ ˜ ˜ ˜ ˜ π R 2 Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ = 0 N 2 R 2 I length Self-inductance L = Φ I = 0 N 2 R 2 length N = L R 2 length 0 N = 6.00 H 10.0 × 10 2 m Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ 2 20.1 × 2 m 1.26 × 6 H / m Ê Ë Á Á Á ˆ ¯ ˜ ˜ ˜ 3.14 = 5520 Answer is rounded to 3 sig figs TOP: SELF-INDUCTANCE 3. ANS: E V rms = 1 2 V peak = 0.707 375 V = 265 V TOP: RMS 4. ANS: C As t →∞ , the field in the inductor becomes saturated and there is no "back emf". Hence, the inductor acts like a short circuit and only R 1 is left. We then have I = V R 1 = 90 V 150 Ω = 6.0 × 1 A = 600m A TOP: RC CIRCUIT CONCEPT 5. ANS: B emf =− d Φ dt d NBA × cos t = NBA × sin t V = max emf Ê Ë Á ˆ ¯ ˜ = NBA = NBA 2 f Ê Ë Á ˆ ¯ ˜ A = V 2 f Ê Ë Á ˆ ¯ ˜ NB 370 V 2 3.14 60
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This note was uploaded on 08/23/2008 for the course PHYS 2b taught by Professor Schuller during the Summer '08 term at UCSD.

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UnitExam5Asolutions - ID: A UCSD Physics 2B Answer Section...

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