A lamp is moved from 15cm to 60cm above the pages of a book. Compare the illumination on the book before and after the lamp is moved. I don't understand this, please explain to me how you've achieved your answer, thanks :)
-
The intensity of light decreases as the distance increases ..
the intensity is inversely proportional to the distance squared ..
so the distance has been increased by a factor of 4 ..
the light intensity has decreased by a factor of 4² = 16
the intensity is inversely proportional to the distance squared ..
so the distance has been increased by a factor of 4 ..
the light intensity has decreased by a factor of 4² = 16