Question

Difference between resolving power and dispersive power of grating

Answer 1

Resolving power of grating:
It's actually the quality of the grating element that how much clearly it is capable of separating two close waves within spectrum.
  The resolving power of grating is normally shown as  λ/dλ

Dispersive power of grating:
This is actually can be defined easily by the ratio . It the ratio of change in diffraction angle and wavelength change or you can also defined it as the change is diffraction angle per unit change in wavelength .it is expressed as dФ/dλ

Answer 2

In optics, a diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams traveling in different directions. An emerging coloration is a form of structural coloration.

Resolving power of grating is the quality of grating element in how clearly it can separate two close waves in the spectrum.

Dispersive power of grating is defined by the ratio of change in angle of diffraction to the corresponding change in wavelength.

Resolving power = total aperture of the telescope objective x dispersive power.