University:
Santa Fe College
Course:
ETS 2527C | Electromechanical Components and Mechanisms
Academic year:

2024
Views:

64

Pages:

6
Author:

Jabin F.

#EM propagation through ionized (plasma) medium: Plasma: It is a medium that has concentration of +ve and -ve charges. And at least one charge type should be mobile-type. Found in upper atmosphere and ionosphere. Metal: +ve ions (fixed) and -ve electrons (free) can be considered as plasma medium Properties: ε = ε₀, μ = μ₀, D = ε₀E B = μ₀H σ = conductivity J = σE f = 0 σ(ω) = dynamic conductivity. for metals: σstatic = Drude conductivity. = Ne²τ / m Plasma ε = ε₀ or V = V₀sinωt usually ω 1/τ Where: N = charge carrier concentration τ = relaxation time of charge carriers m = mass of charge carriers Page-56 Er(ω) = 1 + (A / (ω₀² - ω² - iωγ)) ⇒ refractive index n = √(εr) where: μr = 1 ⇒ n = √(εr) εr = 1 + (A / ω₀²) * (1 - (ω/ω₀)² - i(ω/ω₀)(γ/ω₀)) ω ω₀ ⇒ ω/ω₀ 1 ⇒ εr = 1 + (A / ω₀²) γ/ω 1 (under given conditions) ⇒ εr is frequency independent and real (non-dispersive) If εr or n or K is not real, then no absorption of wave. option-d: If εr and its conjugate are simultaneously -ve so option-d (X) Ques. 71 Page-78 S = Poynting vector = (E × B) / μ₀ Ohm's law: V = IR → Resistance E = V / I = I(R / l) → Resistance per unit length E = IR = I(R/l) B = (μ₀I) / (2πb) S = (E × B) / μ₀ = (I²R) / (2πb) * (-r̂) Test-2020 Q4EI-76 Page-79 E(r, t) = (1 / 4πε₀) * q * θ(vt - r) * r̂ B(r, t) = 0 Where: θ(n) = { 1 if n > 0 { 0 if n <= 0 ∇²E = (1 / ε₀) * ρ ρ = (q / 4π) * [θ(vt - r) * (1 / r²) + (1 / r) * ∂θ(vt - r) / ∂r] ρ = (q / 4π) * [θ(vt - r) * (1 / r²) + (1 / r²) * δ(vt - r)] P = (q² / 2π) * [δ(vt - r) + (1 / r) * δ(vt - r)] For magnetostatics: ∇ × B = μ₀J For electromagnetic field: ∇ × B = μ₀J + μ₀ε₀ * ∂E / ∂t ∴ B = 0 → 0 = μ₀J + μ₀ε₀ * ∂E / ∂t → J = (2qv / 4πr²) * δ(vt - r) * r̂ (Volume current density of point charge q moving with velocity v along r̂ direction)