### Shortcut Methods

##### 6 : Interference and Diffraction

- When calculating fringe separation ((w)) in interference and diffraction problems, you can use the approximation: $$(w \approx \frac{\lambda D}{d}),$$ where λ is the wavelength of light, (D) is the distance to the screen, and (d) is the separation between the slits or sources.
- This simplifies calculations when you need a quick estimate of fringe separation.