Physics 1 Problem Solutions 251

Physics 1 Problem Solutions 251 - over time. Let = L/R ....

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Chapt. 32 Inductance and Inductors 247 d) Sketch I as a function of time. 031 qfull 00424 3 5 0 tough thinking: RL circuit discharge Extra keywords: a sub-useful question maybe good for tests 5. You have a one-loop circuit with ONLY a resistor R and inductor L : there is no Fxed emf source. At time zero, the current in the circuit is I 0 . a) Draw the circuit diagram. Indicate a Fducial (i.e., reference) current direction. b) Write down Kirchho±’s voltage law for any time for this circuit. HINTS: The voltage drops across the resistor and inductor are both taken in the direction of current ²ow. If there is a actually a voltage rise then the drop turns out to be implicitly negative. c) The equation in the part (b) answer is actually a di±erential equation for current. Solve this equation for I as function of time. HINTS: Remember the initial current is I 0 : i.e., I ( t = 0) = 0. Re-order the equation so that both sides of the equal sign can be integrated
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Unformatted text preview: over time. Let = L/R . You dont need an integrating factor this time. If your current goes to inFnity, you may have made a sign error. d) What is the expression for the initial energy stored in the inductor? e) What is the expression for the power dissipated in the resistor at any time t in terms of variables including t explicitly? f) Integrate the expression for power dissipated in the resistor from time zero to inFnity. Has energy been conserved? 032 qfull 00610 2 3 0 mod math: transformer step-up step-down Extra keywords: transformer, step up, step down 6. You want to step up an AC potential by a factor of 3. a) What turn ratio N secondary /N primary must you use? b) What would be the ratio of the secondary to the primary current?...
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