Double-Split experiment with light

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SUMMARY

The discussion centers on Young's Double-Slit experiment, which demonstrates the interference of light waves. Participants explore why the interference pattern consists of large bands of light and dark rather than being imperceptibly small. The key insight is that the size of the slits relative to the wavelength of visible light allows for the formation of significant interference patterns, as each slit behaves like a point source, creating spherical wavefronts. This results in observable interference bands due to varying path lengths of the waves.

PREREQUISITES
  • Understanding of wave optics principles
  • Familiarity with the concept of interference patterns
  • Knowledge of wavelength and its relation to slit dimensions
  • Basic grasp of light behavior as a wave
NEXT STEPS
  • Research the mathematical formulation of interference patterns in wave optics
  • Explore the role of slit width in determining interference visibility
  • Study the implications of Young's Double-Slit experiment on quantum mechanics
  • Investigate practical applications of interference patterns in modern technology
USEFUL FOR

Students of physics, educators teaching wave optics, and anyone interested in the foundational experiments of quantum mechanics will benefit from this discussion.

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Young's Double-Split experiment shows two waves of light interfering with each other.

However I have a question I was hoping someone can help me with.

Why is it we can see the Interference Pattern with large bands of light and dark?

Would not the waves be so small that the interference pattern would be also very small and not detectable by eye?

I can only guess its something to do with the size of the slits and the wave length of visible light.
 
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If we have narrow slits, then each slit will act like a point source for a new wave. So instead of a plane wavefront, the point source will be spherical (or cylindrical in 2D) wavefront. So the interference results in the differing path lengths that the two point sources experience when the wavefronts combine. For small angles, the change in the path length for the first few fringes is very slight and so we can get interference bands that are much larger than the actual wavelength.

Wikipedia has a good explanation in their article: http://en.wikipedia.org/wiki/Double-slit_experiment#Classical_wave-optics_formulation
 

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