Will closing the slit affect the clarity of observing light interference?

[Josielle Abdilla]

Homework Statement

If a student observes a slit illuminated by a light source, through a slit Sa which is almost closed what will he observe?

Relevant Equations

The answer to this question does not involve any mathematical equations but is mainly descriptive

My guesses are that if slit is almost closed, then the width is comparable to the wavelength and diffraction will occur. does this means that he will observe the slit S clearly or less clearly?

[Picture cleaned up a bit by a Mentor]

 

[Josielle Abdilla]

Any ideas please?

 

[etotheipi]

I am not entirely sure on this question, though there are a few things we can say with reasonable certainty.

Do you know what a double slit diffraction pattern looks like? Then, changing the width of $S_a$ does not affect that diffraction pattern, but it will change the amount of light that passes through $S_a$ and by extension the power transmitted through the second slit. If the eye being 'close' enough is to imply that all transmitted light will be detected by it somehow or another regardless of diffraction out of $S_a$, then the obvious difference to me is the intensity on the retina.

However, the water is muddied by the fact that decreasing the width of $S_a$ also increases the amount of diffraction in that all of the angles to different points in the single slit diffraction pattern increase. I'm not sure if this is also meant to be taken into account.

Perhaps someone more knowledgeable with optics will comment later on!

 

[Josielle Abdilla]

Thanks