The magnitude of the Poynting vector of a planar electromagnetic wave has an average value of 0.724 W/m².What is the maximum value of the magnetic field in the wave? (c = 3.0 × 10⁸ m/s,μ₀ = 4π × 10^-7 T ∙ m/A,ε₀ = 8.85 × 10^-12 C²/N ∙ m²) A)77.9 nT B)55.1 nT C)38.9 nT D)108 nT E)156 nT

Question

Quizplus · Accepted Answer

The average Poynting vector S_avg is related to the maximum magnetic field B_max by the equation S_avg = (1/2) * c * ε_0 * E_max^2, where E_max = c * B_max. Solving for B_max gives B_max = sqrt(2 * S_avg / (c * μ_0)). Substituting the given values, B_max = sqrt(2 * 0.724 / (3.0 × 10^8 * 4π × 10^-7)) ≈ 77.9 nT.

The Magnitude of the Poynting Vector of a Planar Electromagnetic