physicsrepost
posted by Stephy .
An owl has good night vision because its eyes can detect a light intensity as small as 5.0*10^13W/M^2. What is the minimum number of photons per second that an owl eye can detect if its pupil has a diameter of 8.5nn and the light has a wavelength of 510nm?
Can anyone please give me some ideas to do it? THANKS A LOT!

The energy into the owl eye is given, multiply that by the area of the eye.
Now the will be the energy per second.
To find the number of photons, planck's equation
Energy above*numberPhotos=hc/lambda
solve for the number of photons.