Diffraction

High School

Definition

The spreading out of waves as they pass through a narrow opening or around the edge of an obstacle. Diffraction is greatest when the opening is similar in size to the wavelength, and it provides evidence that light behaves as a wave.

Worked examples

Sound waves passing through a doorway spread into the room beyond, letting you hear someone speaking even when you can't see them.

The doorway opening is similar in size to the sound wavelength, so diffraction spreads the waves around corners.

A laser beam shining through a narrow slit produces a bright central band with fainter bands on each side on a screen.

Light diffracts through the slit, creating an interference pattern that proves light is a wave.

Water waves passing through a harbor entrance spread out in circular arcs once inside the harbor.

The narrow entrance causes the straight wave fronts to diffract and spread in all directions.

Common mistakes

Diffraction only happens with light waves → Diffraction happens with all waves—sound, water, light, radio, etc. Any wave diffracts when it encounters an opening or obstacle of appropriate size relative to its wavelength.
Diffraction is strongest when the opening is much larger than the wavelength → Diffraction is greatest when the opening is similar in size to the wavelength Large openings produce minimal diffraction; waves pass through almost straight with little spreading.
Diffraction and refraction are the same thing → Diffraction is spreading around obstacles; refraction is bending when entering a new medium Refraction requires a change in wave speed in different materials; diffraction happens at edges and openings.

Where you'll use it next

You'll apply diffraction when studying wave interference patterns, analyzing single-slit and double-slit experiments in physics, understanding how telescopes and microscopes are limited by diffraction, and exploring quantum mechanics where particles exhibit wave diffraction.

Found in 1 StudyPug lesson

Mastering Diffraction and Interference of Light

Physics 11

Dive into the fascinating world of light wave behavior. Understand diffraction, interference patterns, and their applications in modern technology. Enhance your physics knowledge with clear explanations and examples.

11th Grade11th