Exam3_2002Fall_Solutions

# Exam3_2002Fall_Solutions - 8.02T Exam #3 Mashup Fall 2002...

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8.02T 1 Exam #3 Mashup Fall 2002 Solutions Question 1.1: An uncharged capacitor is connected to a dc voltage source via a switch. A resistor is placed in series with the capacitor. The switch is initially open. At t = 0 , the switch is closed. A very long time after the switch is closed, the current in the circuit is 1. nearly zero 2. at a maximum and decreasing 3. nearly constant but non-zero Question 1.2: A solenoid has turns, length , and radius b with b N d d << . The solenoid is connected via a switch, , to an ideal voltage source with electromotive force 1 S ε . The circuit has total resistance and total self-inductance L. At time the switch is closed. The back-emf due to the solenoid is equal to R 0 t = 1 S e) the product of the self-inductance of the solenoid with the current that flows in the circuit f) the self-inductance of the solenoid. g) Æ the product of the self-inductance of the solenoid with the time rate of change of the current that flows in the circuit (this is the only answer that passes dimensional analysis). h) the product of the current squared with the resistance i) one half the product of the self-inductance with the current squared

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8.02 Fall 2002 Exam 3 Mashup Solutions 2 Question 1.3: In an LC circuit, the electric and magnetic fields are shown in the figure. At the moment depicted in the figure, the energy in the circuit is stored in j) The electric field and is decreasing k) Æ The electric field and is constant (there is no resistor: no energy dissipation) l) The magnetic field and is decreasing m) The magnetic field and is constant (3-6 are all wrong – no current, so no B -field) n) In both the electric and magnetic field and is constant o) In both the electric and magnetic field and is decreasing Question 1.4: The curve below shows data taken in a driven RLC circuit experiment. The horizontal axis is the time axis. The solid curve represents the voltage. The dotted curve represents the current. This circuit acts p) Æ inductively (inductors cause the current to lag the voltage).
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## This homework help was uploaded on 04/07/2008 for the course 8 8.02 taught by Professor Hudson during the Fall '07 term at MIT.

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Exam3_2002Fall_Solutions - 8.02T Exam #3 Mashup Fall 2002...

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