Answer: Energy flux (power per unit area) of an EM wave, S = E × B/μ_0.
- A Energy flux (power per unit area) of an EM wave, S = E × B/μ_0
- B The force exerted on a single point charge by the field
- C The electric field energy density alone, ignoring the magnetic part
- D The magnetic field energy density alone, ignoring the electric part
Correct answer: A. Energy flux (power per unit area) of an EM wave, S = E × B/μ_0
Explanation: Poynting vector S = (1/μ_0)(E × B). Its magnitude is the intensity (W/m²) and its direction is the propagation direction of the EM wave.
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.