From water waves to light waves

So far, we have learned that the particle theory and the wave theory of light both predict the observed phenomena's of light. However, as we saw, neither theory could account for all observed phenomenon’s. So, for more than 100 years, both remained in conflict until Thomas Young’s double slit experiment.

What was not known during Newton’s and Huygens time was how small the wavelength of light really was. However, during Young’s time this was better understood. As such, Young used this knowledge to construct a better experimental apparatus that could show that light did in fact behave like a wave.

Conclusion: Light is a Wave!

Recall for water waves:

Minima (Dark Band)

However, this expression accounts only for

destructive interference; what about constructive

interference?

Constructive interference occurs when the

incoming waves have a path difference of

Thus,Maxima (Light Band)