Answer: W/m².
- A W/m²
- B W/m
- C J/m²
- D N/m²
Correct answer: A. W/m²
Explanation: Intensity = power per unit area = W/m². The intensity of sunlight at Earth surface is approximately 1000 W/m² (solar constant ≈ 1361 W/m² above atmosphere).
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.