Answer:
self-contained, short-term light-source
Explanation:
Complete Question
The complete question is shown on the first uploaded image
Answer:
The wavelength is
Explanation:
From the question we are told that
The distance of the slit to the screen is 
The order of the fringe is m = 6
The distance between the slit is
The fringe distance is 
Generally the for a dark fringe the fringe distance is mathematically represented as
![Y = \frac{[2m - 1 ] * \lambda * D }{2d}](https://tex.z-dn.net/?f=Y%20%20%3D%20%5Cfrac%7B%5B2m%20%20-%201%20%5D%20%2A%20%20%5Clambda%20%2A%20%20D%20%20%7D%7B2d%7D)
=> ![\lambda = \frac{Y * 2 * d }{[2*m - 1] * D}](https://tex.z-dn.net/?f=%5Clambda%20%20%3D%20%20%5Cfrac%7BY%20%2A%20%202%20%2A%20%20d%20%7D%7B%5B2%2Am%20%20-%20%201%5D%20%2A%20%20D%7D)
substituting values
=> ![\lambda = \frac{0.019 * 2 * 0.9*10^{-3} }{[2*6 - 1] * 5}](https://tex.z-dn.net/?f=%5Clambda%20%20%3D%20%20%5Cfrac%7B0.019%20%2A%20%202%20%2A%20%200.9%2A10%5E%7B-3%7D%20%7D%7B%5B2%2A6%20%20-%20%201%5D%20%2A%20%205%7D)
=> 
