What is the current I(3τ), that is, the current after three time constants have passed? The current in the circuit will approach a constant value Ic after a long time (as t tends to infinity). What is Ic?

Respuesta :

Complete Question

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Answer:

a

[tex]I(\tau)=0.051 A[/tex]

b

[tex]I(3 \tau)=0.076 A[/tex]

c

[tex]I_c= 0.08 A[/tex]

Explanation:

From the question we are told that

                [tex]I(t) = \frac{e}{R}(1-e^{\frac{t}{\tau} }) ; \ Where \ \tau = L/R[/tex]

From the question we are told to find [tex]I(\tau)[/tex] when t=0  equals the time constant ([tex]\tau[/tex])

That is to obtain [tex]I(\tau)[/tex].This  is mathematically represented as

                   [tex]I(\tau = t) = \frac{\epsilon}{R} (1- e^{-\frac{\tau}{\tau} })[/tex]

             Substituting 12 V for [tex]\epsilon[/tex] and 150Ω for R

                     [tex]I(\tau) = \frac{12}{150} (1- e^{-1})[/tex]

                            [tex]=0.051 A[/tex]

From the question we are told to find [tex]I(3 \tau)[/tex] when t=0  equals the 3 times the  time constant ([tex]\tau[/tex])

That is to obtain [tex]I(3\tau)[/tex].This  is mathematically represented as

                 [tex]I(\tau = t) = \frac{\epsilon}{R} (1- e^{-\frac{3\tau}{\tau} })[/tex]

                  [tex]I(\tau) = \frac{12}{150} (1- e^{-3})[/tex]

                        [tex]=0.076 A[/tex]

As tends to infinity [tex]\frac{\infty}{\tau} = \infty[/tex]

So [tex]I_c[/tex] would be mathematically evaluated as

               [tex]I_c=I(\infty) = \frac{12}{150} (1- e^{- \infty})[/tex]

                   [tex]= \frac{12}{150}[/tex]

                   [tex]= 0.08 A[/tex]

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