• Support PF! Buy your school textbooks, materials and every day products Here!

Grating Resolution

  • Thread starter Gee Wiz
  • Start date
  • #1
137
0

Homework Statement


Considering larger objects, a skyscraper has two tall antennae separated by 3 meters. Each antenna has one blue and one red light. You can resolve the two blue lights but not the red ones.

Assume that your pupils have a diameter = 2 mm at night, and that blue light's wavelength is 475 nm, while red light's wavelength is 650 nm.
Approximately how far are you from the skyscraper? (Also assume that you have 'perfect vision' limited only by diffraction.)

Physics114HWB21_3S.gif



Homework Equations



θ=1.22λ/D

Δλ/λ=1/(mN)

The Attempt at a Solution



I know the answer is 10km, but I don't know how to get that. I was trying to find a way to determine the resolution requirement, or something like that.
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,847
1,644
There is a minimum angular separation that you can resolve two objects - it depends on the wavelength of the light and the diameter of the aperture. You should have some notes on this under "resolving power".
 

Related Threads on Grating Resolution

Replies
1
Views
4K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
5
Views
5K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
993
  • Last Post
Replies
1
Views
1K
Top