If the wavelength of visible light were around \(10 \mathrm{~cm}\) instead of \(500 \mathrm{~nm}\) and we could still see it, what effect would this have on our ability to see diffraction and interference effects?

Imagine you're speaking through the edge of a door that's slightly ajar. You may notice that your voice bends around the edge, becoming audible to someone on the other side, even if they aren't directly in your line of sight. This bending of waves, when it comes across an obstacle or passes through an opening, is referred to as diffraction. Light, like sound, exhibits this wave behavior.

When light encounters a small slit or an edge, it spreads out rather than moving in a straight line. This effect is particularly significant when the size of the obstacle or opening is comparable to the light's wavelength. If the wavelength of visible light were as large as 10 cm, approximately the size of a football, the bending around everyday objects, like a hand or a book, would be quite evident. Visual cues like sharp shadows would blur, creating a world that seems to be painted with broad strokes of a brush rather than fine lines.

In educational terms, helping students visualize diffraction can be improved by encouraging them to picture light as water waves that bend around obstacles in a ripple tank. These tank exercises vividly demonstrate diffraction patterns and how they change with different wavelength sizes.

Have you ever thrown two stones into a pond and watched the ripples from each stone interact with one another? This phenomenon is called interference, and light waves can interact in a similar fashion. When two or more light waves meet, they can combine to form a pattern of bright and dark spots known as an interference pattern.

Interference can be constructive, where waves add together to make a brighter light, or destructive, where they cancel each other out, leading to darkness. In the classroom, we can simulate this concept with laser pointers and double slits, producing clear lines of bright and dark on a screen. This setup is akin to the famous Young's double-slit experiment, a fundamental demonstration of light's wave-like properties.

If the wavelength of light were about 10 cm, the interference patterns created when light waves overlay would be scaled up massively. In a sense, it would be like turning the patterns displayed in Young's experiment into a full-scale art installation, where the contrast between light and dark would become a feature of everyday life.

The term 'visible light' refers to the range of electromagnetic waves that the human eye can detect, usually defined as wavelengths from about 380 nm to 750 nm. To put it into perspective, the average human hair is approximately 100,000 nm wide, so the waves of visible light are incredibly small.

A shift in the scale of visible light's wavelength to 10 cm would be akin to expanding a wave from the size of a pencil tip to the length of a guitar. Such long wavelengths would dramatically change the way we perceive the world. Colors themselves are a result of the varying wavelengths within the visible spectrum, with blue light having shorter wavelengths and red light having longer wavelengths. If visible light had a wavelength of 10 cm, our entire perception of color would shift, and the world would likely be perceived in a much different palette. It's important for students to grasp that wavelength is directly tied to our sensory experience of light and color.