Light from a helium-neon laser (λ = 633 nm) is used to illuminate two narrow slits. The interference pattern is observed on a screen 2.5 m behind the slits. Eleven bright fringes are seen, spanning a distance of 54 mm. What is the spacing (in mm) between the slits?

The  value is  

Explanation:

From the question we are told that

   The wavelength is  

    The  distance of the screen is  

    The  order of the bright fringes is   (10  fringe + central maximum = eleven bright fringes )

      The distance between the fringe is  

Generally the condition for constructive interference is  

=>    

Now  from the SOHCAHTOA rule the angle   is mathematically represented as

So  

=>      

=>      

answera compound;