The values of the circuit parameters are not specified , except that E = 81 V. I
ID: 1755843 • Letter: T
Question
The values of the circuit parameters arenot specified, except that E = 81 V.
In the circuit above, the switch S is initiallyopen. At t = 0, S is closed. At t = 1.2 ms, thecurrent through the battery is I = 6 A . After a longtime, this current reaches a steady-state value I = 12A.
= s
R =
Explanation / Answer
GIVEN: E = 81 V I = 6 A @ t = 1.2 ms =1.2e-3 sec (I) = 12 A @ t = ITEMA: Current "I" thru the series resistor-inductor circuit at time "t" is given by the following formula. We substitute the given problem data and solve for time constant "". I = (I)*(1 - exp(-t/)) ----> (6) = (12)*(1 -exp(-(1.2e-3)/)) ( {TimeConstant} = = 1.731e-3 sec ITEMB: Using Ohm's Law {"E = I*R"} together with the properties of a resistor-inductor circuit, we determine R: R = E/(I) ----> R = (81)/(12) ----> {Resistor} = R = 6.75 Ohms ITEMC: From the definition of resistor-inductor time constant"" (thevalue for which was determined in Item A), we obtain: = L/R ----> L = R* ----> L = (6.75)*(1.7312e-3) ----> {Inductor} = L = 0.01169 Henry .Related Questions
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