The bending of a wave as it moves around an obstacle or passes through a narrow opening.

• A. Wavelength
• B. Diffraction
• C. Energy
• D. Amplitude

Answer: (B)

Diffraction is the bending and spreading of a wave as it encounters an obstacle or passes through a narrow opening. This happens with light, sound, and water waves, so you can see it when light waves bend around edges or when sound travels through a small gap. The amount of bending depends on the wavelength compared to the size of the obstacle or opening—the more similar they are in size, the more the wave spreads out after passing through. Wavelength, amplitude, and energy describe other aspects of waves: wavelength is the distance from crest to crest, amplitude is how tall the wave is, and energy relates to the work the wave can do. Diffraction specifically explains the bending and spreading behavior.