Wave refraction is the bending of waves as they pass from one medium to another, causing a change in their speed and direction. This occurs because the wave's speed changes as it moves through media with different densities or properties.
Understanding the Process
When a wave encounters a boundary between two different media (e.g., deep water to shallow water, or air to water), a portion of the wave may be reflected, but a significant part will continue to travel into the new medium. This transition causes a change in the wave's speed. If the change in speed is not uniform across the wavefront (the imaginary line connecting points of equal phase), then the wave bends.
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Slower Speed, More Bending: If a wave slows down as it enters a new medium, the portion of the wavefront that enters first will slow down before the rest, causing the wave to bend towards the area where it's traveling slower. This is commonly seen with ocean waves approaching a shoreline. Water waves travel faster in deep water than in shallow water. As the wave approaches shallower water, it slows down, and the wave bends toward the shore.
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Faster Speed, Less Bending: Conversely, if a wave speeds up, the wave bends away from the area where it speeds up.
Examples of Wave Refraction
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Ocean Waves: As mentioned above, ocean waves are a prime example. They refract as they approach the shore due to the change in water depth. This often results in wave energy being concentrated on headlands and dispersed in bays. Instructional videos explain this process clearly.
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Light Waves: Light waves refract when they pass from air into water, or through lenses. This principle is fundamental to how lenses in eyeglasses or cameras work. This analogy holds true for all types of waves.
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Sound Waves: Sound waves also experience refraction when they pass through media with varying densities, such as air at different temperatures or through layers of different materials.
Key Factors Affecting Refraction
The amount a wave bends is determined by:
- The change in wave speed.
- The angle at which the wave strikes the boundary between the media. The initial direction of wave propagation relative to the change in medium affects refraction.
Refraction, or the bending of waves, is accompanied by a change in speed and wavelength. This change in direction is due to the interaction with the medium. Some of the wave may be reflected, but a portion will pass into the new medium.
