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: The minimum number of photons per second?

  1. May 22, 2010 #1
    1. The problem statement, all variables and given/known data

    An owl has good night vision because its eyes can detect a light intensity as small as 4.5 10-13 W/m2. What is the minimum number of photons per second that an owl eye can detect if its pupil has a diameter of 7.5 mm and the light has a wavelength of 503 nm?

    2. Relevant equations

    I'm not really sure how to begin. Can you help me solve this step by step?

    Photons per sec= Energy per sec/Energy per photon ??

    3. The attempt at a solution
  2. jcsd
  3. May 22, 2010 #2


    User Avatar
    Homework Helper

    Sure, that'd be a good start.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook