Resolvant Power of a Dİffraction Grating

[sigmaro]

Homework Statement

What is the resolvent power (R) of a diffraction grating?

Homework Equations

R=(Δλ)/λ
asin(θ)=mλ

The Attempt at a Solution

as we all know answer is Nm here N is the number of slits
there is something starting with
a sin(θ)(Δθ)=mΔλ but it gets stuck

 

[gneill]

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/gratres.html"

 

[sigmaro]

i had checked that but it is not much satisfying

 

[sigmaro]

come on guys its been a long time, not anyone?