Reading wavefront diagrams and diffraction patterns
≈ 48 minReading wavefront diagrams and diffraction patterns
Wavefront diagrams should be read as maps of phase and direction. The propagation direction is perpendicular to a wavefront, and the spacing between successive wavefronts represents wavelength in a uniform drawing. After diffraction through a narrow gap, curved fronts spread over a larger angle; after a wide gap, the central fronts remain more nearly straight. Do not confuse a diffraction pattern with a refraction diagram: diffraction occurs around an aperture or obstacle in the same medium, while refraction requires a boundary and speed change. In an exam sketch, show enough wavefronts to make curvature, spacing and direction interpretable.
Work it through
A set of straight wavefronts reaches a single narrow gap. Draw semicircular wavefronts centred at the gap on the far side. If the source frequency and medium are unchanged, keep the spacing equal to the incoming wavelength. The direction at each point is perpendicular to the curved front, so different parts of the wave now travel in different directions.
Mastery target
Interpret or sketch a wavefront diagram with correct propagation direction, wavelength spacing and diffraction curvature.
What is the direction of wave propagation relative to a wavefront?
Name the key physics term from Reading wavefront diagrams and diffraction patterns that best fits the explanation and visual model.
Which change is expected after water waves pass through a narrow gap in the same medium?
Which statement corrects a common misunderstanding in Reading wavefront diagrams and diffraction patterns?