interference in thin films
Eduphile・22 minutes read
Film interference occurs when two light waves meet and interfere within transparent materials, creating interference patterns with dark and bright fringes. The interference requires coherent light sources, and the calculation of path difference involves optical path difference and refractive indices.
Insights
- Films exhibit interference patterns when light reflects and transmits within them, creating bright and dark fringes influenced by the light source's spectrum.
- Understanding interference in films requires controlling path differences between two coherent light sources, utilizing concepts like optical path difference and refractive indices to determine interference patterns with precision.
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Recent questions
What is film interference?
Film interference occurs when light reflects and transmits within films.
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Summary
00:00
Understanding Film Interference in Light Waves
- Film interference is discussed in detail, focusing on the concept, notes, working, derivation, and step-by-step explanation.
- Films are transparent materials like bubbles or oil on water, where interference occurs when light reflects and transmits within them.
- Interference happens when two reflected lights meet and interfere due to the wave nature of light.
- Films are typically on the order of a wavelength in thickness, crucial for interference to occur.
- Natural film exhibits interference patterns with light waves reflecting and interfering with each other.
- Interference patterns can show dark and bright fringes, influenced by the light source's spectrum.
- In lab settings, monochromatic light is used for film interference experiments to control interference patterns.
- Interference requires two coherent sources, like S1 and S2, to create interference patterns.
- Path difference between two waves determines interference patterns' maximum and minimum brightness.
- Path difference calculation involves understanding the optical path difference and refractive indices to determine interference patterns.
11:28
Angle Relationships and Interference in Optics
- The angle in front of the angle is always perpendicular, so Tan R = BG / Fug.
- BG = F G 10 R, and since Fug = t, BG becomes t10 R.
- B = 2 10 2 T 10 R, as B is double when equal to A.
- In triangle BHD, HD is perpendicular, making BHD 90°.
- I in BHD is equal to I in the triangle, due to parallel lines.
- Optical path difference is 2μ t cos R.
- For constructive interference, 2μ cos R = 2 m + 1 λ / 2, while for destructive interference, 2μ cos R = 2 m + 1 λ / 2.
