Double Slit Experiment: Does Slit Thickness Matter?

  • Context: High School 
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Discussion Overview

The discussion revolves around the double slit experiment, specifically questioning whether the thickness of the slits affects the interference pattern produced by electrons. The conversation includes theoretical considerations and practical implications related to the experiment.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Simon questions if the thickness of the slits, particularly if they were a meter deep, would influence the interference pattern observed in the double slit experiment.
  • Some participants, including Simon and another contributor, suggest that the thickness should not matter, drawing analogies to classical waves where the path length is the critical factor.
  • Another participant argues that very thin slits are necessary to observe distinct interference patterns, implying that thicker slits might obscure the pattern due to closely occurring constructive and destructive interference.
  • Simon mentions a student's reasoning related to delaying observation by using long slits in the direction of travel, which raises questions about the nature of observation in quantum mechanics.
  • A later reply introduces the concept of the quantum eraser and the delayed choice quantum eraser, suggesting a more complex understanding of observation's role in the experiment.

Areas of Agreement / Disagreement

Participants express differing views on the impact of slit thickness on interference patterns, with no consensus reached. Some believe thickness does not matter, while others argue that it could affect the visibility of the patterns.

Contextual Notes

The discussion includes assumptions about the nature of observation in quantum mechanics and the dependence on definitions of "thickness" and "slit." There are unresolved questions regarding the implications of using long slits and the mechanics of observation.

SimonB
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Hi

A question that came up today that I do not know how to answer. We were discussing (High School) the double slit experiment and that electrons show interference patterns too. A student asked if the thickness of the double slit slide mattered. ie if the slits were a metre deep ... would this effect the pattern (my assumption is no ...)

Thanks for any comments

Simon
 
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My intuition says no as well. Immagine classical waves of water traveling town two adjacent canals. Unless there is a difference in the path leingth, each wave would act as a point source when exiting the far side.
 
To notice patterns you need very thin slits, if you have thick slits you won't be able to notice any change since construction destruction all occur so close together.
 
Thamks atavistic ... however the student considered thick in the direction perpendicular to the screen, along the direction of motion
 
SimonB, since you're the teacher, you may care to look up how to actually calculate the interference pattern (and not just the positions of the maxima). As for the students benefit, you could try demonstrating a laser pointer directed through more than one double-slit slide, or if you have less equipment, directed through one or two hairs from your (student's?) head (or parallel to the surface of small slips of paper).
 
Thanks, I will of couse be doing the usual stuff.

I have talked to the student and his reasoning is as follows.

We had watched a video clip for electron interference. It described how the interference pattern is destroyed when the electron is observed entering one or other slit. The electron being disturbed by the observation. His reasoning was to use very long (in direction of travel) slits so the observation could be delayed ...
 
SimonB said:
..being disturbed by the observation. His reasoning was to...
Yeah, that way lies madness.. but is very interesting provided you're careful. You might want to look up the $10 quantum eraser, or the delayed choice quantum eraser. (I recommend against thinking of the observation as mechanically disturbing the system, and concentrate more on how much external information is present about the system. And of course, study classical waves in detail.)
 

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