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question about light absorption

Discussion in 'Homework Help' started by kkhh, Jan 3, 2013.

  1. kkhh

    Thread Starter New Member

    Jan 2, 2013
    . The absorption coefficient for GaAs at λ = 633 nm is α = 3×10^6m-1
    . Find, what percentage of the incident light will pass through the layer, the thickness of which is:
    1) 200 nm; 2) 500 nm; 3) 1 µm; 4) 2 µm; 5) 10 µm;
    i have tried solving the question but didn't find it in the materials
    i have found I=I0exp(-ax)
    where a is absorption cofficient and x s the thickness

    thank you very much
  2. Brownout

    Well-Known Member

    Jan 10, 2012
    Try a physics forum.
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Beer Lambert law,

    a=your molar extinction co-efficient
    b=thickness of sample
    c= concentration

    Since concentration is always constant, set it equal to 1. Your co-efficient is in micrometers so re-adjust all sample thicknesses to micrometers.
  4. WBahn


    Mar 31, 2012
    Q1) This should be in the Homework Help section.

    Q2) What are your attempts to answer the question?

    Q3) What does I=Io*exp(-ax) tell you?

    Q4) What are you looking for?

    Q5) What is the difference between the answers to Q3 and Q4?