Wave Model for Light

Section 8.8 Wave Model for Light

Up to this point, you have been using the ray model for light, which assumes that light travels in straight lines, somewhat like an ordinary particle of matter. It turns out that light can be a little more complicated than that.

Light can also be described as a wave! The wave-particle duality of light is extremely useful, especially when the wavelength of light is comparable to the size of any mechanism or object the light is interacting with. In these cases, you will use the wave nature of light to explain what you are seeing.

Principle 8.8.1. Huygen’s Principle.

Every point along a wave front can be considered a source of a waves emanating from that point in the direction of light propagation.

A single slit of width a sits horizontally. A straight line sits inside the slit, parallel to the slits. Seven dots are evenly distributed across this line. Multiple concentric half circles extend outwards from each point, travelling upwards. — Figure 8.8.2. A diagram of Huygen’s Princple. As light travels through an opening, each point along a wave front can be understood as a source of waves.

Exercises Wave Model Activities

1. Wave Interference.

Spend some time playing with the light interference simulation. Click on the "Interference" tab, and on the right hand side, choose the laser pointer option.

Make some observations as you are playing with the simulation. What happens if you separate the lasers as far as possible? What happens if you bring them as close together as possible? What happens when you change the frequency?

References References

[1]

The Original Double Slit Experiment by Veritasium.

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