A non-reflective coating that has a thickness of 198 nm (n = 1.45) is deposited on top of a substrate of glass (n = 1.50). What wavelength of visible light is most strongly transmitted if it is illuminated perpendicular to its surface?

The  wavelength is

Explanation:

From the question we are told that  

      The  thickness is

      The refractive  index of the non-reflective coating is    

       The  refractive  index of glass is

Generally the condition for  destructive  interference is mathematically represented as

Where is the angle of refraction which is  0° when the light is strongly transmitted

    and  n is the order maximum interference

        so  

at the point n =  1  

at  n =2  

Now we know that the wavelength range of visible light is  between

   So the wavelength of visible light that is been transmitted is  

ill do it for 100, also this isnt 80 its 40