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Refraction vs Diffraction:  What’s the Difference?

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refraction and diffraction as laser beam moves through crystal

We usually think of different measures as specific quantitative types, such as degrees, feet, or pounds. When speaking of energy, the common denominator is waves, whether it’s sound, light, or electromagnetic sources. The terms refraction and diffraction describe their behavior. They provide the basis for quantifying them and making them meaningful in their respective fields. It’s a way to measure risk, which is necessary for survival.

Knowing the difference between refraction and diffraction allows scientists to describe patterns and develop theories about their behavior. That has profound implications for the application of various technologies. 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.

In short, refraction is a light ray or energy wave bends when it passes from one medium to another. Diffraction is when light rays go around opaque objects or through narrow openings, causing the light to look like it has been deflected.

telescope divider 2

Refraction vs Diffraction: At a Glance

Refraction Diffraction
Through one medium to another Going around an object
Electromagnetic or physical Electromagnetic or physical
Bulk phenomenon Edge phenomenon

Overview of Refraction:

a pencil in a glass of water, an example of refraction
Image Credit: ScienceGiant, Pixabay

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. You are observing it in air and water, two different media. The term describes the wave movement and what we see as a result.

The results are the interaction of the two elements involved and their varying characteristics. The definition implies a graduating scale, which does exist. You can see it in the starkness of the contrasts between the two things. Those differences can prove helpful when differentiating between the components and offer interesting insights into them. A prism or microscopes are other common examples through different media.

Overview of Diffraction:

light diffraction glasses pinholes
Image By: Nikolai Shtepsel, Shutterstock

On the other hand, Merriam-Webster differentiates diffraction as “a modification which light undergoes especially in passing by the edges of opaque bodies or through narrow openings and in which the rays appear to be deflected.” You see examples every day with shadows. The light can’t get through an object, so it takes the path of least resistance around it.

The results are clear, and it’s apparent from the shadows’ existence that the object is opaque: light isn’t getting through it because it can’t. It finds the easiest pathway around it instead of through it. This information is helpful when detecting unknown substances. The results tell a lot about the chemical properties of unknown substances or objects. Both light and sound waves undergo the effects of either type.

Diffraction influences the speed of the light wavelengths, affecting what you see. The result is varying appearances of the targeted objects because of these effects. Things may look different as a result. This effect brings them into clear focus since the differentiation between the specimen and the surrounding environment is so stark. That makes them easy to see.

Other Factors to Consider

Refraction versus diffraction is not a trait you can control. A substance is either one or the other. Instead, its usefulness comes from knowing what each one designates and what it can tell you about the varying chemical properties. It can make a critical difference in the development of experiments and the identification of vital ingredients.

Interestingly, both types expose the varying wavelengths of visible light, which makes them different colors. What you’re seeing is the various results of the action affecting them. The spectrum of visible light runs from wavelengths of 380 to 740 nanometers. That explains the varying colors you’ll see. The density of the target affects the diffraction properties.

The difference between refraction and diffraction makes the two stand out for what they reveal. As you may expect, each of them has different applications. That makes the comparison between the two difficult since you can’t substitute one for another in most cases. You’re relying on one or the other for the identification of two similar specimens.

Image Credit: Autumnwar, Shutterstock

telescope divider 2 Conclusion

The difference between refraction and diffraction is more of a description between the wave sources and their interaction with the elements to which it is exposed. Refraction provides a reflection of the varying opaque nature of the two. Diffraction describes a situation where one component is a barrier. Instead of an avenue, it becomes an obstacle that diverts the waves. It’s a reminder that no evidence is evidence of a conclusion.

Featured Image Credit: Daniele Levis Pelusi, Unsplash

About the Author Chris Dinesen Rogers

Chris has been writing since 2009 on a variety of topics. Her motto with all of her writing is “science-based writing nurtured by education and critical thinking.” Chris specializes in science topics and has a special love for health and environmental topics, and animals of all shapes and sizes.