Suppose `10^(-18)`J of light energy is needed by the interior of the human eye to see an object. How many photon of green light (`lambda` = 550nm) are needed to generate this amount of energy ?

Answer

3

Explanation

`E_("photon") = (hc)/(lambda) = (6.625xx10^(-34)xx3xx10^8)/(550xx10^(-9))`
`=3.61xx10^(-19) J = `1 Photon
`10^(-18) J = (10^(-18))/(3.61xx 10^(-19)) = (10)/(3.61) = 2.77 = 3`