Field intensity: Near the earth the intensity of radiation from the sun is 1.35 kW/m². What volume of space in this region contains 1.0 J of electromagnetic energy? (c = 3.0 × 10⁸ m/s, μ₀ = 4π × 10^-7 T ∙ m/A, ε₀ = 8.85 × 10^-12 C²/N ∙ m²) A) 4.5 × 10^-6 m³ B) 3300 m³ C) 7.4 × 10^-4 m³ D) 1400 m³ E) 220,000 m³

Question

Quizplus · Accepted Answer

The energy density (u) is given by u = I/c, where I is the intensity. So, u = 1.35 kW/m² / (3.0 × 10⁸ m/s) = 4.5 × 10⁻⁶ J/m³. The volume V containing 1.0 J is V = 1.0 J / 4.5 × 10⁻⁶ J/m³ = 220,000 m³.

Field Intensity: near the Earth the Intensity of Radiation from the Sun