Water waves diffract when they bend around obstacles or spread out after passing through openings. This bending occurs because wave energy propagates outwards from the source. When a wave encounters a barrier or gap, its energy isn't completely blocked. Instead, it spreads out, a phenomenon known as diffraction.
Understanding Water Wave Diffraction
Diffraction is a characteristic behavior of all waves, including water waves, sound waves, and light waves. The amount of diffraction depends on two primary factors:
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Wavelength: Longer wavelengths diffract more significantly than shorter wavelengths. Think of it this way: a long wave has more "room" to bend around an obstacle.
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Size of the Obstacle or Opening: The smaller the gap or obstacle relative to the wavelength, the more pronounced the diffraction. If the opening is much larger than the wavelength, diffraction is minimal. Conversely, if the opening is comparable to or smaller than the wavelength, the diffraction is more significant.
This is why you'll observe more noticeable diffraction effects with larger ocean waves encountering small piers compared to small ripples passing by a large rock.
Examples of Water Wave Diffraction
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Ocean waves bending around jetties: Ocean waves readily diffract around jetties and other coastal structures, spreading the wave energy into areas that would otherwise be sheltered. (Wikipedia)
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Waves passing through a narrow gap: If waves encounter a narrow opening, they spread out after passing through it. This is readily observable in a ripple tank experiment. (Physics Classroom)
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The effect of wavelength on diffraction: The amount a wave bends depends on its wavelength. Longer waves (larger wavelength) diffract more readily than shorter ones. (Physics Forums)
The diffraction of water waves is a consequence of the wave nature itself. Waves propagate as a distribution of energy, and this energy naturally spreads out when encountering obstacles or openings. (Physics Stack Exchange). This spreading is greater when the wavelength is larger compared to the size of the obstacle or opening. (Surfer Today)
