About thin film (max bright/dark)

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Homework Help Overview

The discussion revolves around the behavior of light in a thin film of SiO2, particularly focusing on the conditions for bright and dark fringes in interference patterns. Participants are exploring the relationship between the thickness of the film and the wavelength of light, as well as the implications of phase changes upon reflection.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to relate the thickness of the SiO2 wedge to the observed interference fringes and questioning the meaning of variables such as "t." There is also a focus on understanding the conditions for bright and dark fringes, with some participants seeking clarification on the thickness at specific points of the wedge.

Discussion Status

The discussion is ongoing, with participants providing insights into the relationship between thickness and fringe patterns. Some have offered clarifications about the variable "t" and its significance, while others are still seeking a deeper understanding of the concepts involved.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the information available for discussion. There is an emphasis on understanding the setup and definitions related to thin film interference.

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Homework Statement


擷取2.PNG

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Homework Equations

The Attempt at a Solution


SiO2 as the thin film,when light entry SiO2 and Si then the reflected light has 180 phase change,
for dark fringes
2nt=(m+1/2)λ
for bright fringes
2nt=mλ
for dectect max of bright/dark,-1<=sinx<=1, then no idea to prove father[/B]
 
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Relate the thickness of the wedge to the wavelength of light ... notice there are seven fringes, so how many wavelengths of light thick is the widest part of the wedge?
 
Simon Bridge said:
Relate the thickness of the wedge to the wavelength of light ... notice there are seven fringes, so how many wavelengths of light thick is the widest part of the wedge?
could you possibly explain more? still not understand..
 
kenok1216 said:

The Attempt at a Solution


SiO2 as the thin film,when light entry SiO2 and Si then the reflected light has 180 phase change,
for dark fringes
2nt=(m+1/2)λ
for bright fringes
2nt=mλ[/B]
Do you know what "t"means?
How thick is the oxide at the thinnest part?
 
ehild said:
Do you know what "t"means?
How thick is the oxide at the thinnest part?
t=the thick of SiO2
 
kenok1216 said:
t=the thick of SiO2
The SiO2 thickness changes, as it is a wedge. You see a bright strip where the thickness t matches the condition 2nt = mλ.
How thick is the SiO2 wedge at the thinnest part? Do you see it bright or dark?
 

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