This lecture explains how to calculate the resolution power of a network of slits with interference, by applying the definition and formula for resolution power, which is the smallest difference between two wavelengths normalized by the wavelength. The instructor demonstrates how to find the resolution power for a network of n slits with interference at the mth maximum, and how to infer the second order and number of slits based on given values. By combining equations, the lecture shows how to calculate the delta wavelength and determine the closest value to the nominal wavelength.