Question

Please help 11th grade.

A 55 W car headlight has a brightness of 1. 39 W/m² at some unknown distance away. What would the intensity of the

light be if it were measured at half the original distance to the headlight?

Answer 1

I = K / R^2 intensity at distance R is inversely proportional to R^2

I2 / I1 = (R1 / R2)^2 = 1 / (1/2^2) = 4

The intensity at 1/2 the distance would be"

I = 4 * 1.39 W/m^2 = 5.56 W/m^2