# Double Slit Experiment: Does Slit Thickness Matter?

• SimonB
In summary, the student's reasoning was that if the electron is disturbed by the observation, the interference pattern will be destroyed.
SimonB
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

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.)

## 1. What is the double slit experiment?

The double slit experiment is a classic physics experiment that demonstrates the wave-like nature of light and matter. It involves shining a beam of particles (such as photons or electrons) through two parallel slits and observing the interference pattern that is produced on a screen behind the slits.

## 2. How does the double slit experiment work?

In the double slit experiment, a beam of particles is shone through two slits and produces a pattern on a screen behind the slits. This pattern is created due to the wave-like behavior of the particles, as they diffract and interfere with each other. The resulting pattern is an interference pattern, with areas of constructive and destructive interference.

## 3. What is the purpose of the double slit experiment?

The purpose of the double slit experiment is to demonstrate the wave-particle duality of matter. It shows that particles, such as photons or electrons, can behave like waves and exhibit interference patterns, rather than just behaving like individual particles.

## 4. Does slit thickness matter in the double slit experiment?

Yes, slit thickness does matter in the double slit experiment. The size of the slits affects the diffraction and interference patterns that are produced on the screen. Thicker slits will result in a wider interference pattern, while thinner slits will produce a narrower pattern.

## 5. How does changing the slit thickness affect the interference pattern in the double slit experiment?

Changing the slit thickness can alter the interference pattern in the double slit experiment. Thicker slits result in a wider interference pattern with lower contrast, while thinner slits produce a narrower pattern with higher contrast. This is due to the diffraction of the particles as they pass through the slits, which affects the interference pattern they create.

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