A uniform wave delivers 6.0 mW to a detector area of 2.0 cm². Define intensity and calculate it. A second wave in the same medium at the same frequency has three times the displacement amplitude; what is its intensity and how much power reaches that same detector? Explain the distinction between area and amplitude.

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Intensity is power per perpendicular area. I₁=30 W m⁻²; I₂=270 W m⁻²; P₂=0.054 W=54 mW. Area is the collecting surface, amplitude the maximum oscillatory displacement. Define intensity with area perpendicular to propagation. Convert 2.0 cm² to 2.0 × 10⁻⁴ m² and 6.0 mW to 0.0060 W. Calculate 30 W m⁻². Use squared-amplitude factor 3²=9, giving 270 W m⁻². Calculate IA=0.054 W and distinguish the two meanings.

Separate collecting area from wave amplitude

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