Suppose `10^17 J` of energy is needed by the interior of human eye to see an object. How many photons of green light `(1 = 550 nm)` are needed to generate this minimum amount of energy ?

Options

A. 14
B. 28
C. 39
D. 42

Answer

B

Explanation

(b) Let the number of photons required be `n`.
`(nhc)/(lamda) = 10^-17`
`n = (10^-17 xx lamda)/(hc) = (10^-17 xx 550 xx 10^-9)/(6.626 xx 10^-34 xx 3 xx 10^8)`
=`27.6 ~= 28 "photons"`.