A distance R away from a light source we observe which of the following for the electromagnetic field it produces? A) Both the light intensity and the magnitude of the electric field drop as 1/R₂. B) The light intensity drops as 1/R₂, but the magnitude of the electric field drops as 1/R. C) Both the light intensity and the magnitude of the electric field drop as 1/R. D) The light intensity drops as 1/R, but the magnitude of the electric field drops as 1/R₂. E) None of the previous answers is correct.

Question

Quizplus · Accepted Answer

The intensity of light drops as the inverse square of the distance (1/R^2) due to the spreading out of the wave over a larger surface area (like the surface of a sphere). The magnitude of the electric field drops as the inverse of the distance (1/R) due to the weakening of the wave as it spreads out. Therefore, option B is the correct choice as it takes both of these factors into account.

A Distance R Away from a Light Source We Observe