- #1
charlesh
- 2
- 0
Homework Statement
Light consisting of two nearly equal wavelengths L and L+dL, where dL << L, is incident on a diffraction grating. The slit separation of the grating is D. Show that the angular separation of these two wavelengths in the m'th order is dTheta = dL / ((D/m)2+L2)0.5
Homework Equations
D sin(Theta) = mL (m=0,+-1, +-2,...)
The Attempt at a Solution
D sin(Theta1)=m(L+dL)
D sin(Theta2)=m(L)
dTheta = sin(Theta1)-sin(Theta2) = (m/D)(L+dL-L) = (m/D)dL= dL/(D/m)
This answer doesn't match the formula I need to proof: dTheta = dL / ((D/m)2+L2)0.5