Answer: δ = √(2/μσω) where σ is conductivity.
- A δ = √(2/μσω) where σ is conductivity
- B δ = c/f, the plain vacuum wavelength formula with no conductivity term
- C δ = λ/(2π), the formula for the radian wavelength in vacuum
- D δ = λ, equating the skin depth directly to the free-space wavelength
Correct answer: A. δ = √(2/μσω) where σ is conductivity
Explanation: Skin depth δ = √(2ρ/μω) = √(2/μσω). For copper at 60 Hz, δ ≈ 8.5 mm. At 1 MHz, δ ≈ 0.07 mm. This limits AC current to the conductor surface at high frequency.
In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.
Concept context
Maxwell's equations, EM spectrum, properties, and applications of each band.