Two different double‐slit assemblies, A and B, are available in a laboratory.
• Assembly A: slit separation 0.30 mm, screen distance 1.6 m
• Assembly B: slit separation 0.20 mm, screen distance 1.0 m
Both assemblies are illuminated by the same red laser with wavelength 635 nm.
(a) Derive an expression for the ratio of the spacing between adjacent bright regions produced by assembly A to the spacing produced by assembly B.
(b) Calculate this ratio numerically.
(c) Based on your result, predict which assembly would allow more precise measurements of small displacements on the screen and justify your choice.