0

Guest

Courses New

monochromatic beam of light of wavelength 663nm is incident normal to the surface produces a pressure of 10^-6 N/m^2. the surface absorbs 75% of light and reflects the rest. find the number of photons per unit area per second:

monochromatic beam of light of wavelength 663nm is incident normal to the surface produces a pressure of 10^-6 N/m^2. the surface absorbs 75% of light and reflects the rest. find the number of photons per unit area per second:

Grade:12th pass

1 Answers

mahima pareek
20 Points
5 years ago
The expression for pressure exerted when there is reflection and absorption is 
        P = I(1 + r) /c
Where P = pressure exerted 
             I = intensity of the incident light
             r = reflection coefficient 
            c = speed of light
Here r = 100 - 75/100 = 0.25
Now we know 
           I = nE/Atc 
Where.   n = no.  of photons incident 
               E = energy of each photon 
                A = area of the metal plate 
                t = time of incidence of photons 
Now we are given P and asked about n/At
So our formula for pressure becomes 
         P =( The thing which is asked) E(1 + 0.25)/c
Now n/At = Pc/E(1.25)
                  Answer is probably 9.84 * 10 to the power 20
 
PS i did not solve it as I don't have special characters in phone 
Approve if the asnwer is correct 
  

Think You Can Provide A Better Answer ?

Other Related Questions on Modern Physics

View all Questions »

ASK QUESTION

Get your questions answered by the expert for free

Answer and earn gift vouchers

Win Gift vouchers upto Rs 500/-

View courses by askIITians

Design classes One-on-One in your own way with Top IITians/Medical Professionals

Click Here Know More

Complete Self Study Package designed by Industry Leading Experts

Click Here Know More

Live 1-1 coding classes to unleash the Creator in your Child

Click Here Know More

a Complete All-in-One Study package Fully Loaded inside a Tablet!

Click Here Know More