1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Significance of wavelength

  1. Jun 19, 2010 #1
    1. The problem statement, all variables and given/known data

    what is the physical significance of wavelength (not the definition)?

    2. Relevant equations

    in photodetectors (like avalanche or p-i-n photo diodes) incident light having more wavelength,
    penetrates more in the diode (particularly in depletion region : )

    so, how this more penetration for higher wavelength can be described?

    3. The attempt at a solution
  2. jcsd
  3. Jun 20, 2010 #2
    How is energy of light related to wavelength? And what is the relation between this energy and the bandgap of the semiconductor?
  4. Jun 20, 2010 #3
    light enrgy is related to its own wavelength.

    but for more wavelength,
    incident light penetrates the photo-detectors more in their depletion region.
    my question is how this more penetration for more wavelength can be described,
    the physical significance of it.
  5. Jun 20, 2010 #4
    Well penetration means it isn't absorbed. So you have to think of what can cause absorption in a semiconductor and how does this relate to the energy of the light.
  6. Jun 20, 2010 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    A light wave can be thought of as a repeating pattern of electric and magnetic fields, propagating through space. The wavelength is related to that pattern.
  7. Jun 20, 2010 #6
    so, what can be realised by wavelength, from this thought?
    what is the difference for longer wavelength?
  8. Jun 20, 2010 #7


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Have you been taught about sine and cosine functions in school, and the period of a sine or cosine graph? Those are the concepts that come in to play here.

    Since this appears to be a homework assignment, we don't just hand out answers. That's why I'm providing conceptual hints to help you think about what is going on.
  9. Jun 20, 2010 #8

    having sine and cosine graph concept and period ....

    why light having more wavelength penetrates more?
    like why infrared is used for shorter distance than bluetooth?

    because of shorter wavelength of infrared.
    why short wavelength light is unable to penetrate more?
    this is my question, you can say.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook