A specified volume of space contains an electric field for which the magnitude is given by E=E0cos(ωt). Suppose that E0 = 20 V/m and ω = 1.0 × 107 s−1. What is the maximum displacement current through a 0.40 m2 cross-sectional area of this volume?

Respuesta :

Answer: [tex]0.708\ mA[/tex]

Explanation:

Given

[tex]E_o=20\ V/m[/tex]

[tex]\omega =10^7\ s^{-1}[/tex]

Cross-sectional area [tex]A=0.40\ m^2[/tex]

Current density is given by

[tex]J=\epsilon_o \dfrac{dE}{dt}[/tex]

Displacement current

[tex]\Rightarrow I=JA\\\Rightarrow I=8.854\times 10^{-12}\times 20\times 10^7\times 0.4\\\Rightarrow I=0.708\times 10^{-3}\ A[/tex]

The required value of the maximum displacement current of the given space is  [tex]7.08 \times 10^{-4} \;\rm A[/tex].

Given data:

The intensity of electric field is, [tex]E_{0}=20 \;\rm V/m[/tex].

The angular frequency of electric field is, [tex]\omega=1.0 \times 10^{7} \;\rm s^{-1}[/tex].

The cross-sectional area of space is, [tex]A =0.40 \;\rm m^{2}[/tex].

In the given problem, the instantaneous electric field is given by [tex]E = E_{0} \times cos(\omega t)[/tex]

So, the expression for the current density is,

[tex]J= \epsilon_{0} \times \dfrac{dE}{dt}[/tex]

Here, [tex]\epsilon_{0}[/tex]  is the permittivity of free space. Solving as,

[tex]J= \epsilon_{0} \times \dfrac{d(E_{0} \times cos(\omega t))}{dt}\\\\J= -\epsilon_{0} \times E_{0} \times \omega \times sin(\omega t)[/tex]

And the expression for the maximum displacement current is,

[tex]I = J \times A[/tex]

And the maximum displacement current is possible only when, J is positive and J will be positive for  [tex]sin(\omega t)=-1[/tex].

Then solving as,

[tex]I = (-\epsilon_{0} \times E_{0} \times \omega \times sin(\omega t)) \times A\\\\I = (-8.85 \times 10^{-12} \times 20 \times (1.0 \times 10^{7}) \times (-1)) \times 0.40\\\\I = 7.08 \times 10^{-4} \;\rm A[/tex]

Thus, we can conclude that the required value of the maximum displacement current of the given space is  [tex]7.08 \times 10^{-4} \;\rm A[/tex].

Learn more about the displacement current here:

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