Chapter 36 - Diffraction - Problems - Page 1111: 34a

Red

First we consider equation (36-14) $\theta_R= \frac{1.22\lambda}{d}$ We can see that larger values for the wavelength, $\lambda$, will create larger values of $\theta_R$. Because red light has the largest wavelength light, the angle of the rings will increase and we will see red rings on the outer edges of the diffraction maxima.