IB Physics: Optical Resolution and the Rayleigh Criterion, Topic 9.4

[@mandygoat8493]

you are SOOO saving me rn

[@belindaflorie1929]

Thank you so much for your videos. Such a help with this course

[@donerphysics]

Glad it was helpful!

[@mandygoat8493]

Youre the best

[@justinho2807]

Hi, at 21:07, you are using the formula \theta= 1.22lambda/b, but I don't understand why \theta is s/d. And thank you for these amazing videos it genuinely helps a lot.

[@yahyahammoudeh1944]

theta is s/d as the triangle is a right angle triangle, take the opposite over the adjacent and that is sin(theta), for small theta it is equal to sin(theta)

[@justinho2807]

@@yahyahammoudeh1944 Thanks! so it's the small angle approximation.

[@danoptical2382]

Hi I would like to ask, theoretically the resolution angle is constant, or does it change if the two source points are not at infinity but at a short distance from the lens?

[@jasonfong7394]

Great video! Thanks!

[@donerphysics]

Glad you liked it!

[@filippofonseca]

How come at 29:31 we are using the second order maximum? how do we know that? I get that 28.3 is greater than 2, but why 2?

[@donerphysics]

We need for mN to be larger than R=998. N=900, so the lowest order maximum that will resolve is m=2.

[@bozkurt-wick]

Hello Mr. Doner, It came to my attention that a portion of your older "free" videos (before the membership feature) were listed as Members-only. I wanted to ask why did this change occur, as I usually revise for exams using your physics videos since a little more than a year. I thought only the new videos you made would be for members, not the old free ones from 2013.

[@donerphysics]

Some of the new videos were set to public (i.e. Doppler Effect and Resolution) I made individual decisions for other videos (i.e. some videos could not be monetized, so I switched them to member's only videos so that they could help to garner some income.) Most of the old videos remain public but there are likely to be some inconveniences. I am now retired and have a wife and disabled daughter to care for, so this income has become important to me.

[@bozkurt-wick]

I'm sorry to hear that Mr. Doner. I hope you get the recognition you deserve. Keep up the great work 💪

[@donerphysics]

Thanks!

[@ashar4121]

At around 20:09, why does s/d equal theta? It's obviously not a right triangle.

[@donerphysics]

It is a small angle approximation that the triangle is essentially a sector of circle, and the definition of an angle in radians is the arc length divided by the radius.

[@ashar4121]

@@donerphysics thank you!

[@mandygoat8493]

I love you

[@EmielRegisRochellecTerzief]

it is easier to make... angular separation of our maxima bigger than something that's small than it is to make it bigger than something that's a little bit bigger

[@mandygoat8493]

I love u