# B Double slit question, rotating polarizers..

1. Nov 18, 2016

### mister mishka

I've wondered about this for sometime, say you rotate one of the polarizers (one of the two covering each slit) slowly from perpendicular to parallel, would the interference pattern slowly come into view?

2. Nov 18, 2016

### BvU

3. Nov 18, 2016

### mister mishka

Ok, but what happens if both polarizers are perpendicular and you introduce a third larger polarizer before the two slits and slowly rotate that? Would you ever see an interference pattern? Say at 45 degrees to the polarizers perpendicular to one another? Kind of like how polariscopes work..

Thanks for any answers, I unfortunately do not know math well enough to understand, but I want to just know ("see") what the result is. Maybe its possible for me to do this experiment myself, but I will google it and see..

4. Nov 18, 2016

### DrChinese

When there are 2 separate polarizers in front of the slits, the interference is controlled by those - and not the 3rd large one. That one serves primarily to adjust the intensity of the resulting pattern. Obviously you have to look at the math (a la Malus) to get the exact effect as you vary 3 settings.

5. Nov 18, 2016

### mister mishka

I was thinking the 2 perpendicular polarizers being behind the slits, and polarized light shining through the slits first (at 45 degrees). However maybe the slits themselves act as a polarizer? Yeah, I think I need to study a bit tonight.. I will see what type of math I need to learn, and inevitably how long that will take :p