# In Young's double slit experiment, does the intensity of light depend on the slit width?

Here's a question I just came around
In YDSE, the intensity of the maxima is I.If the width of each slit is doubled, what will be the intensity of maxima now ?
here, we assume that no diffraction is occurring.

what I thought was that the intensity is power per unit area, therefore even though more light is coming in but the area factor will cancel it hence the intensity must remain same.

But the answer was 2I and was according to the direct relation of slit width and the intensity of light.

please tell where I m wrong?

Also, I saw a proof online where the person is treating two dependent variables as independent.

Here's the link check it too.

• @Farcher but the OP says "no diffraction is occurring", which means geometric optics, which means they're not slits, they're big holes, which mean the intensity doesn't change.
– JEB
Commented Sep 29, 2019 at 15:27
• @JED I take your point. Commented Sep 29, 2019 at 15:44
• @JED I want to clarify we are just assuming that diffraction is not happening, although it will happen in reality... Commented May 20, 2020 at 13:42
• @Farcher I want to clarify we are just assuming that diffraction is not happening, although it will happen in reality... Commented May 20, 2020 at 13:42

So the answer is $$2I$$.