Answer:

Explanation:
Given,
Width of slit, W = 5.7 x 10⁻⁴ m
Distance between central bright fringe, L = 4 m
distance between central bright fringe and first dark fringe, y = 4 mm
Diffraction angle



Now.

m = 1



My guess would be choice D
2 thing it is used for are commonly like wind turbines and water turbines.
I believe the answer is potential difference