I'm carrying out an experiment about interference and diffraction with double slit (multiple slits in a future) in a ripple tank.

I have the chance to 3d print the slits so I'm thinking about the best configuration of them. I have measured the wavelength of different frequencies wavelengths ranging from 0.83 cm to 2.2cm. So the distance from center to center from one hole to the next cannot be less than 2.2, in fact it should be less to be able to appreciate the interference correctly, since the vision inside the tank is limited to the area illuminated by the lamp. I have thought about 5cm, as we think that I can get great values with in all range of frequencies. Would you make it smaller?

Another doubt that I had is that i was thinking that the width of the middle slit should be 2cm, so the hole width is 3cm. But after thinking about it a little more I believe that the hole would be better if it is smaller. For example, doing the middle slit width 4cm, and the hole 1cm. What do you think about it?

All these doubts come from that today I tried to measure the angle of interference with the defaults slits of the ripple tank (2cm width of the hole and the slit is 3cm width), and my results did not match those theoretically expected. I attach the image of the experiment with , maybe it's a measurement error instead of the slit. In this case the expected angle is $8,3\pm0,6$. It is not too far but it is not in the error margin... Maybe the measurement tool is not correct? If you can give any advice!

Thanks! Experiment

  • $\begingroup$ the smaller the whole the closer it is being an ideal point source with emitting a nearly hemi-spherical (semi-circular) wave. At least in EM, a hole of a size approximately $\lambda/20$ is about as good a point source as can be at that wavelength and it does not matter much from which direction the incident wave comes and hits the hole. If you make the hole larger than $\lambda/5$ then you may have to take into account the phase distribution across the hole, the width of the screen, etc. There is a broad almost "neutral" area in between. $\endgroup$
    – hyportnex
    Feb 28 at 21:53


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