Two identical conducting plates, each having area \(A\), are located at \(z=0\) and \(z=d\). The region between plates is filled with a material having \(z\) -dependent conductivity, \(\sigma(z)=\sigma_{0} e^{-z / d}\), where \(\sigma_{0}\) is a constant. Voltage \(V_{0}\) is applied to the plate at \(z=d ;\) the plate at \(z=0\) is at zero potential. Find, in terms of the given parameters, \((a)\) the resistance of the material; \((b)\) the total current flowing between plates; ( \(c\) ) the electric field intensity \(\mathbf{E}\) within the material.

Short Answer

Expert verified
Question: Calculate the total resistance, total current, and electric field intensity within a material with the following parameters: d = 2 cm, A = 20 cm², σ₀ = 0.04 S/m, and voltage V₀ = 50 V. Step 1: Calculate total resistance R = (d(1 - e)/σ₀A) = (2(1-2.718)/0.04*20) = (2(-1.718)/0.8) = -4.295 Ω Step 2: Calculate total current I = (σ₀AV₀)/(d(1 - e)) = (0.04 * 20 * 50)/(2(1 - 2.718)) = 40/(-3.436) = -11.642 A Step 3: Calculate electric field intensity at z E(z) = (V₀)/(d(1 - e)*e^{z/d}) = (50)/(2(1 - 2.718)*e^{z/2}) (z in cm) The total resistance within the material is -4.295 Ω, the total current flowing between the plates is -11.642 A, and the electric field intensity within the material is given by E(z) = (50)/(2(1 - 2.718)*e^{z/2}) when z is measured in cm.

Step by step solution

01

Compute the resistance

To determine the resistance, we will use the relationship R = ρL/A, where ρ is resistivity, L is the distance between the plates, and A is the area of the plate. Since we are given σ(z), the conductivity, instead of resistivity, we will need to use the relationship ρ(z) = 1/σ(z). The total resistance is obtained by integrating from z=0 to z=d: R = ∫[ρ(z)L/Area]dz = (∫[1/σ(z)]dz)/A Now substitute the expression for σ(z) and integrate with respect to z: R = (∫[1/(σ_{0}e^{-z/d})]dz)/A
02

Evaluate the integral to find the resistance

Now, we will evaluate the integral and solve for R: R = ([-d*e^{z/d}]/(σ_{0}A))|_{0}^{d} Evaluate the limits and simplify the expression: R = ([-d*e^{d/d} - (-d*e^{0})]/(σ_{0}A)) R = ([-d*e^{1} + d]/(σ_{0}A)) So, the total resistance is given by: R = (d(1 - e)/σ_{0}A)
03

Compute the total current between the plates

To find the total current I, we can use Ohm's law V = IR. We already have the resistance R, and we are given the voltage V₀. So, we can rewrite Ohm's law and solve for I: I = V₀/R Substituting the given voltage and the resistance we found in step 2: I = V₀ / (d(1 - e)/σ_{0}A) Solve for the total current I: I = (σ_{0}AV₀)/(d(1 - e))
04

Compute the electric field intensity within the material

To calculate the electric field intensity E within the material, we can use the relationship between current density J and conductivity σ: J = σE. The current flowing between the plates is perpendicular to them, so we need to find the current per unit area: J = I/A Now, substituting the expression for I from step 3 and the expression for the conductivity σ(z): J = (σ_{0}V₀)/(d(1 - e)) σ(z)E(z) = (σ_{0}V₀)/(d(1 - e)) Now, we can solve for E(z): E(z) = (V₀)/(d(1 - e)*e^{z/d}) So, the electric field intensity within the material is given by: E(z) = (V₀)/(d(1 - e)*e^{z/d})

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