The intensity of light from a small lamp is at a distance of . What is the intensity at ?

Answer and explanation

Correct answer: C.

  1. Step 1: Intensity follows an inverse-square law: .
  2. 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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The intensity of light… | ESAT (Engineering and Science Admissions Test)