Chapter 25 - Vision and Optical Instruments - Learning Path Questions and Exercises - Exercises - Page 873: 47

$650nm$

Given there are of two identical monochromatic point sources. Minimum angle of resolution of their diffraction patterns $\theta_{min}=0.0065 rad$ Slit width w = $0.10mm$ $\theta_{min}=\frac{wavelength}{w}$ Therefore, $wavelength = \theta_{min}\times w=0.0065\times 0.1\times 10^{-3}=650\times10^{-9}m=650nm$