A conductor carries a current that is decreasing exponentially with time. The current is modeled as I = I0e−t/τ, where I0 = 7.75 A is the current at time t = 0.00 s and τ = 0.50 s is the time constant. How much charge flows through the conductor (in C) between t = 0.00 s and t = 2τ? (Enter the magnitude.)

Respuesta :

Given:

At t = 0 s and [tex]\tau[/tex] = 0.50s

[tex]I_{o}[\tex] = 7.75 A

I = [tex]I_{o}e^-{\frac{t}{\tau}}[/tex]

Solution:

Now, to calculate the charge flow in the interval t = 0 to t =  2[tex]\tau[/tex]

We know that, electric current is the rate of flow of electric charge and is given by:

[tex]I = \frac{\Delta Q}{\Delta T}[/tex]

[tex]\Delta Q = I\Delta T = I_{o}e^-{\farc{t}{\tau}}[/tex]             (1)

Integrating the above eqn in the interval   t = 0 to t =  2[tex]\tau[/tex]

[tex]\int_{0}^{Q}\Delta Q = \int_{0}^{2\tau}I_{o}e^-{\frac{t}{\tau}}\Delta T[/tex]

Q = [tex][-\tau (I_{o}e^-\frac{t}{\tau})]_{0}^{2\tau}[/tex]

Q = [tex]I_{o}[-\tau e^{-2} + \tau][/tex]

Q = [tex]7.75[-0.50 e^{-2} + 0.50][/tex]

Q = 3.35 C

Therefore, Q = 3.35 C of charge flows through the conductor in the given interval.

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