9?

Asked by smanishkumar2002 | 20th May, 2018, 10:45: PM

Expert Answer:

Question:
 
Suppose 10-17 J energy is needed by interior  human eye to see an object . How many photons of green light (wavelenght =550 nm) are needed to generate this minimum amount of energy?
 
Solution:
 
Given colon

straight E equals space 10 to the power of negative 17 space end exponent straight J

straight lambda space equals 550 space nm

straight lambda equals space 550 cross times 10 to the power of negative 9 end exponent space straight m.

We space have comma

straight E space equals space hc over straight lambda

space space space space space equals fraction numerator 6.62510 to the power of negative 34 end exponent space cross times space 3 cross times 10 to the power of 8 over denominator 550 cross times 10 to the power of negative 9 end exponent end fraction

straight E space equals space 3.61 space cross times 10 to the power of negative 19 end exponent space straight J

No space. of space photons space required space equals fraction numerator 10 to the power of negative 17 space end exponent over denominator 3.61 space cross times 10 to the power of negative 19 end exponent end fraction

No space. of space photons space required space equals space 2.77 cross times 10 squared

No space. of space photons space required space almost equal to space space 28 space photons.
 
 

Answered by Varsha | 21st May, 2018, 10:33: AM