Question

A photographer uses a light meter to measure the intensity of light from a flash bulb. The intensity for the flash bulb,I, in lux, is a function of the distance from the light, d, in meters, and can be represented by I(d)=10/d^2, d>0 determine the approximate instantaneos rate of change in the intensity of light at exactly 3m from flash bulb. determine the approximate instantaneos rate of change in the intensity of light at exactly 3m from flash bulb. 

Answer 1

Assuming lux (I) is I(d)=10/d^2, d>0, then the the photographer should calculate approximate instantaneous rate of change of a light at exactly 3m from a flash bulb to be ((I(3.1)-I(2.9))/(3.1-2.9), using an interval of d between 2.9 and 3.1.