Waves Interference and Wavelength Calculations

[josephcollins]

Hi ppl, could someone please give me a hand with these:

Light of wavelength 400 nm in air falls on two slits 0.05 mm apart. The slits are immersed in water, as is a viewing screen 40cm away. How far apart are the fringes on the screen?(n water is 1.33)

In a double slit experiment it is found that blue light of wavelength 460nm gives a second order maximum at a certain location on the screen. What wavelength of visible light would have a minimum at the same location?

In a water tank experiment, water waves aee generated with their crests 2.5cm apart and parallel. They pass through two openings 5cm apart in a long wooden board. If the end of the tank is 2m beyond the boards, where would you stand, relative to the "straight through" direction, so that you received little or no wave action?

Thanks for any help,
Joe

 

[KaneOris]

Is it you don't know how to do this, or is it you just can't be bothered. First show us an attempt at the question, some working out to where you go to, and we'll give you some hints, tips, and bits of information that will help you out

 

[josephcollins]

okay, for the first question, I have managed to work it out myself having calculated the new wavelength.

For the others, it's how to set up an equation bearing in mind the condition for destructive interference that I can't work out.