1
$\begingroup$

I was just looking out of window at night when i saw a tower with a light on top. It had a red light . When i looked at it through my curtains with net on i saw an interference fringe , one is the main light itself and band of lights on either side of it(like interference of waves). Although there was no screen why did i see it . Did the air acted like screen so i saw it ? Was it because nets of curtain acted like slits , which produced that pattern ?Or is it some other simple diffraction or anything of light . I dont think its because of other simple reason because interference pattern was clear . Any process that can explain this phenomenon?

$\endgroup$
4
$\begingroup$

What you are seeing is an interference pattern, similar to double slits or diffraction gratings. You can confirm this comparing the light pattern when you are looking straight through the curtain (when the curtain is perpendicular to the line from you to the light) and when the curtain is at an angle. Angling the curtain makes the threads appear closer together, so the interference fringes will spread out more.

For the curious, here's what a far off stop light looks like through motel curtains: Stop light through curtains

The pattern is easier to see when the source in monochromatic (LEDs and the like).

$\endgroup$
  • 1
    $\begingroup$ I'll second this. I have observed the same thing on our curtains. They act as a grate. It's easy to reproduce if you point a laser at it. You'll see a beautiful interference pattern on the wall. (You can even calculate the size of the grate from it!) $\endgroup$ – WIMP Dec 16 '17 at 7:30
  • $\begingroup$ but what was acting as screen for the interference pattern to be seen? because the tower i saw was few km away , and the red light was on top. $\endgroup$ – hippozhipos Dec 16 '17 at 9:24
  • 1
    $\begingroup$ @hippozhipos Your retinas are the screen for the interference pattern. $\endgroup$ – Mark H Dec 17 '17 at 2:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.