Diffraction Basics

Ever wondered why you can hear someone calling from around a corner? That's diffraction in action - the spreading out of waves when they encounter gaps or obstacles. The magic happens when the gap size matches the wavelength of the wave.

Here's the key rule: maximum diffraction occurs when the gap equals the wavelength. If the gap's smaller than the wavelength, most waves bounce back. When it's larger, you get less spreading. Think of it like squeezing through a doorway - the tighter the fit, the more you have to "spread out" to get through.

When monochromatic light (single colour) passes through a slit, it creates a stunning interference pattern on a screen. You'll see a bright central fringe that's twice as wide as the others, surrounded by alternating light and dark bands. The bright fringes form through constructive interference (waves working together), while dark fringes result from destructive interference (waves cancelling out).

Quick Tip: Remember that the central maximum is always double-width - this detail often appears in exam questions!

White light diffraction creates something completely different. Since white light contains all colours (all wavelengths), each colour diffracts by different amounts, creating a spectrum pattern. You'll see a white central maximum with coloured fringes either side - violet closest to the centre, red furthest away.

Want to control the pattern? Change the slit width or wavelength. Wider slits create narrower, brighter central maxima with less diffraction. Longer wavelengths produce wider, dimmer patterns as they diffract more easily.