What Do Waves Do When They Refract?

Defintion of Refraction

• Refraction is a term to describe how light or sound bends when it moves from one material to another. The wave bends and changes speed, and the extent to which this happens depends on the properties of the material it is moving into. For example, different densities and dimensions affect how a wave will refract.

Refraction of Light Waves

• The eye is able to see because light waves refract as they pass through the lens of the eye. When light enters the eye, it is moving to a denser material; therefore, as Snell's Law dictates, it slows down and bends. The lens focuses the waves onto the retina to form an image. Glasses or contact lenses refract light in such a way that it focuses more on the retina to improve vision. Put a pencil in a cup of water and look at it from the side. Notice how the pencil appears bent; this is the light refracting -- or slowing down and bending -- to distort the shape.

Refraction of Water Waves

• Water waves refract at different angles and speeds, depending on the depth of the water. In this sense, the change in depth of the water represents a new medium. This is because the dimensions of the water are different. If a wave travels from deep to shallow water, it slows down, as described by Snell's Law. This decreases the wavelength, which is visible as a reduction in the physical size of the wave.

Refraction of Sound Waves

• Just as light waves change speed and direction when they move through different materials, sound waves behave the same way. Cold air is denser and slows down sound more than warmer air. Imagine a person shouting to you from a distance. You hear an amplified or echo sound as the person speaks. This is because sound waves have entered your ears from different directions; each of the waves has traveled at a different speed, depending on the route through the air it took. As such, an amplification or echo is heard.