Resolving Power Of Telescope — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Resolving Power of Telescope Used in Wave Optics to determine the ability of a telescope to form separate images of two distant point objects that are close to each other. Light passing through a circular aperture of diameter D undergoes diffraction. The angular position of the first dark ring (minimum) is given by θ ≈ 1.22 λ / D. Two point sources are resolved if their angular separation Δθ is at least this angle (Rayleigh Criterion). Resolving Power is defined as the reciprocal of this limit of resolution: RP = 1 / Δθ = D / (1.22 λ). Applies specifically to circular apertures. Assumes diffraction-limited optics (no aberrations). Based on the Rayleigh criterion where the first minimum of one diffraction pattern coincides with the central maximum of the other. Confusing Resolving Power with Magnifying Power. High magnification does not guarantee high resolution if D is small. Thinking that larger wavelength improves resolution; actually, smaller wavelength (e.g., blue light) yields higher resolving power. Omitting the factor 1.22, which is specific to circular apertures (as opposed to slits).