The intensity of light from a small lamp is at a distance of . What is the intensity at ?
Answer and explanation
Correct answer: C.
- Step 1: Intensity follows an inverse-square law: .
- Step 2: The distance is multiplied by , so the intensity is divided by .
Answer
.
Why not the others: : treats intensity as inversely proportional to distance. : takes the ratio of distances as . : divides by the distance itself.
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