In a thin film experiment, a wedge of air is used between two glass plates. If the wavelength of the incident light in air is 480 nm, how much thicker is the air wedge at the 16th dark fringe than it is at the 6th dark fringe

The thickness is  

Explanation:

From the question we are told that

   The wavelength is  

    The first order of the dark  fringe is  

     The second order of dark fringe considered is  

Generally the condition for destructive interference is mathematically represented as

Here y is the path difference between the central maxima(i.e the origin) and any dark fringe

So  the path difference between the 16th dark fringe and the 6th dark fringe is mathematically represented as

=>  

=>  

=>  

any one of the statements could be an accurate comparison. but the statement that would define the correct choice and seal the deal is not even on the list:

"the visibilities of vector-x and vector-y in the drawing provided with the question are identical and nonexistent."