A prism or microscopes are other common examples through different media. Those differences can prove helpful when differentiating between the components and offer interesting insights into them. You can see it in the starkness of the contrasts between the two things. The definition implies a graduating scale, which does exist. The results are the interaction of the two elements involved and their varying characteristics. The term describes the wave movement and what we see as a result. You’re observing it in air and water, two different media. Merriam-Webster defines refraction as a “deflection from a straight path undergone by a light ray or energy wave in passing obliquely from one medium (such as air) into another (such as glass) in which its velocity is different.” A classic example is a spoon in a glass of water. Overview of Refraction: Image Credit: ScienceGiant, Pixabay Diffraction is when light rays go around opaque objects or through narrow openings, causing the light to look like it has been deflected. In short, refraction is a light ray or energy wave bends when it passes from one medium to another. The two types have varying uses, which makes comparison more of a view of these applications than one of one being better than the other. That has profound implications for the application of various technologies. Knowing the difference between refraction and diffraction allows scientists to describe patterns and develop theories about their behavior. It’s a way to measure risk, which is necessary for survival. They provide the basis for quantifying them and making them meaningful in their respective fields. The terms refraction and diffraction describe their behavior. When speaking of energy, the common denominator is waves, whether it’s sound, light, or electromagnetic sources. We’ve been using sound as an example since it has a much longer wavelength (from a few centimetres to a few metres depending on the frequency) and so objects such as the edges of walls will cause diffraction and enable sound to travel round corners.We usually think of different measures as specific quantitative types, such as degrees, feet, or pounds. We can set up specialised experiments in the lab to demonstrate light diffraction, but if you’re in the shadows on a sunny day, diffraction around the obstruction to the direct sunlight is not going to get you a tan. Light waves have a very small wavelength (typically 500 nm, although of course it changes with colour) and diffract noticeably in everyday life. Seats in a theatre or stadium are on a slope so you can see and hear well. If you’re behind someone tall, then not only do you not get to see the musicians, you also get less direct sound from the stage because it has to diffract around the tall person’s head. Going back to acoustics, you’ll want to avoid this shadowing effect when you go to see a band or orchestra play. This is another way of picturing the bending that diffraction describes. This can’t happen, some of the waves must get into the flat water. If the water inside the harbour stayed dead calm, then somewhere near the harbour mouth you would see completely flat water immediately next to big waves. Some of the energy will reflect, but at the end of the barrier (near the opening of the harbour) the waves will bend around and come inside. If you live near the sea, have a look at waves on a windy day hitting a harbour wall. Acoustic Consultant, Vicky StewartĬareer case study: Why Vicky chose to study acoustical engineeringĪ really good example of diffraction can be seen with another type of wave barrier – a harbour or dock wall. One mitigation measure I proposed was to use the villa’s own infinity swimming pool to screen the traffic sound, acting like a noise barrier. The developer was worried about the noise from a road. One of my favourite projects was for the developer of luxury holiday villas in the hills just outside Paphos, Cyprus. Photo © Robin Stott ( cc-by-sa/2.0) Case study: an unusual noise barrier Sometimes the barriers are made of earth, in which case they’re called a bund. Look out for heavily-built fences along the side of motorways – these are noise barriers. But low frequencies are less attenuated by the barriers because they can diffract (bend) over the top. Noise barriers alongside roads reduce the traffic sound for houses in the shadow zone. Because if you stand there you are in an acoustic shadow (just like the optical shadows we see) and the sound is quieter.Īcoustic shadow zones are exploited by acoustical engineers to reduce noise. In acoustics, we use the term shadow zone to describe the area behind the object. At high frequency, when the wavelength is small compared to the object size, then the sound does not diffract very effectively.
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