How do wave behaviours contribute to rainbows?

Wave behaviours, specifically refraction, reflection, and dispersion, contribute to the formation of rainbows.

Rainbows are a natural phenomenon that occur when sunlight interacts with raindrops in the atmosphere. The wave behaviours of light, including refraction, reflection, and dispersion, play a crucial role in this process.

When sunlight encounters a raindrop, it first undergoes refraction as it enters the droplet. Refraction is the bending of light as it passes from one medium to another, in this case from air to water. The light wave slows down and changes direction as it enters the water droplet due to the difference in the speed of light in air and water.

Inside the raindrop, the light wave reflects off the inner surface. This reflection causes the light wave to bounce back towards the other side of the droplet. However, not all the light exits the droplet at this point. Some of it undergoes a second reflection, bouncing back again towards the first side of the droplet.

As the light wave exits the droplet, it refracts again, this time from water back into air. This second refraction causes the light wave to speed up and change direction once more.

The dispersion of light also plays a key role in the formation of rainbows. Dispersion is the process by which white light is separated into its constituent colours due to the different wavelengths of light refracting at slightly different angles. This is why rainbows display a spectrum of colours, from red on the outside to violet on the inside.

The combination of these wave behaviours results in a circular arc of light appearing in the sky opposite the sun. Each raindrop contributes a tiny part of the rainbow, with the colour observed depending on the angle of the sunlight as it enters and exits the droplet.

In summary, the wave behaviours of refraction, reflection, and dispersion are fundamental to the formation of rainbows. These processes cause sunlight to be bent, reflected, and separated into different colours as it interacts with raindrops in the atmosphere.