making double slit

[Itoero]

I would like to do the double slit experiment.

How big can the distance between the two slits maximum be?

Can I make the double slit with 3 toothpicks?

 

Can I show the particle behavior using a laserpointer and a self made double slit?

[swansont]

The distance has to be comparable to the wavelength of light. For visible light, more than a few microns will make it tough to see.

 

I've done it with a laser pointer and a piece of aluminum foil that had the slits cut into it by hand. The pattern wasn't great, but it existed.

[Sensei]

I have two setups bought in shop.

 

One has slit width 30 um (0.03 mm), distance between centers of slits 60 um (0.06 mm).

Second one has slit width 50 um (0.05 mm), distance between centers of slits 100 um (0.1 mm).

 

They need to be precisely done..

Otherwise in-accurateness will be greatly influencing results, and further calculations.

 

[imatfaal]

.Can I show the particle behavior using a laserpointer and a self made double slit?

 

No - you will at best be able to show wave-like behaviour not particle-like behaviour; remember Young's experiment was designed in the time of the disagreement between Huygen's wave structure of light and Newton's corpuscular. Fresnel building on Young's work succeeded in convincing most of the science community that Huygen's waves were the correct model.

 

Overly simplistically - If they were particles (acting classically) you would get two strips of lights aligned with the direct path (with blurring when there was a slight reflection off the edge of the slit. But what you actually get is an interference pattern - to demonstrate the particulate side of the nature of a quantum mechanical entity you need which-way information (or some other form of breaking the interference).

 

Last time I actually did this experiment was 25 years ago - and then buying a pre-slitted blackened piece of glass was pocket-money cheap.

[Itoero]

ok:)

On YouTube I saw a video in which someone used 3 pencil leads as double slit.

Isn't a pencil lead a lot wider then the wavelength?

[swansont]

ok:)

On YouTube I saw a video in which someone used 3 pencil leads as double slit.

Isn't a pencil lead a lot wider then the wavelength?

For slits with large separations the issue is the coherence of the light. Light from one slit has to be able to interfere with light from another one. If the separation is e.g. 500x the wavelength, then you'll be OK only if the light is coherent over that length. If you had perfectly coherent light, there would be no maximum. But generally speaking you won't have that. There isn't going to be a hard-and-fast answer without knowing your light source. You typically get the best results with smaller separations.

 

Someone using pencil leads that are 300 um or 500 um thick and seeing interference has a decent laser pointer. Other ones might not work.

[Eise]

Can I show the particle behavior using a laserpointer and a self made double slit?

 

No.

[Itoero]

I'm using a red laserpointer with 5mW.

I just watched a video in which someone uses the transparant part of a dvd...which contains small slits, separated only a few micrometers.

 

What distance between slits and screen should I take? A couple meters?

[swansont]

I'm using a red laserpointer with 5mW.

I just watched a video in which someone uses the transparant part of a dvd...which contains small slits, separated only a few micrometers.

 

What distance between slits and screen should I take? A couple meters?

The further you are away the greater a separation you will see. You can use this to find whatever parameter you want

 

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/slits.html