The bending of a wave around an obstacle is known as

• A. Diffraction
• B. Deflection
• C. Refraction
• D. Reflection

Answer: (A)

Diffraction is the bending and spreading of waves as they encounter obstacles or openings. When a wavefront meets an edge, parts of the wave pass by the edge and the resulting wavelets interfere, causing the wave to bend around the obstacle and spread into the region behind it. This effect is most noticeable when the obstacle or slit is comparable in size to the wavelength, as smaller wavelengths produce less visible bending. You can see it in water waves curling around a rock, sound waves bending past a doorway, or light forming fringes when passing through a small slit. By contrast, refraction refers to bending due to a change in speed when a wave enters a different medium, reflection is the bouncing of a wave off a surface, and deflection isn’t the standard term used for this wave behavior.