Question

The Intensity I, of light received at a source varies inversely as the square of the distance,d,from the source, If the intensity if 53 foot-candles at 45 feet, find the intensity at 9 feet?

Answer 1

`=1325` foot-candles

Explanation:

Intensity at `9 feet=(45/9)^2times 53`

`=(5)^2 times 53`

`=25 times 53`

`=1325`