A soap bubble is 115 nm thick and illuminated by white light incident perpendicular to its surface. What wavelength (in nm) and color of visible light is most constructively reflected, assuming the same index of refraction as water (nw = 1.33)?

The  wavelength is and the color is  Orange

Explanation:

from the question we are told that  

     The thickness is

      The refractive index of water is  

Generally the condition for constrictive interference is  

Where   is the wavelength of light in a particular medium

  Now considering the medium of water(soap bubble )

 The  wavelength of light in this medium is mathematically represented as

So  

=>    

substituting values  

The color is orange because the wavelength range of yellow is  

       590–625 nm

e) none of the above answers are correct