Telescopes - A Level Physics

[@DrPhysicsA]

Indeed. Singing and physics go well together.

[@DrPhysicsA]

I'm Dr Robert Eagle CBE BSc PhD (London). I studied Physics at King's College and followed up with a PhD in Nuclear Physics. You can follow me on Twitter where my tweets are random, occasionally interesting and even more occasionally about physics - BobEagle2

[@acho8387]

I have a different question. Does that pen have infinite ink?

[@DrPhysicsA]

+Angel Angelov Alas no. I have several pens.

[@visharora4934]

at 30:21 shouldn't the rays on the outer edge of the spherical mirror be focused nearer to the mirror? Just the way i've been taught, not sure who's right....

[@DrPhysicsA]

Yes you are probably right. I was simply making the point that they don't all come to the same point.

[@mahmoudm451]

I didn't understand that minimum angle separation between the 2 light rays inorder to resolve them thingy. If anyone can explain I will be thankful!

[@DrPhysicsA]

Try my video on "Waves - A level Physics" starting at 18:16.

[@KakarotM99]

will the derivation from 00:00 to 09:40 work for microscope

[@Dyslexic-Artist-Theory-on-Time]

Nice video! This is an invitation to see an artist theory on the physics of light and time! This theory is based on two postulates 1. Is that the quantum wave particle function Ψ represents the forward passage of time ∆E ∆t ≥ h/2π itself 2. Is that Heisenberg’s Uncertainty Principle ∆×∆p×≥h/4π that is formed by the w- function is the same uncertainty we have with any future event that we can interact with turning the possible into the actual!

[@taptythemighty]

I love the way he says theta! Thank You for the great revision videos!

[@DrPhysicsA]

Thanks. I oscillate between the English theeter and the American thayta.

[@fakhruddi1]

at 4:46 What happened to the 3rd ray?????

[@al-oh8fq]

it was heading top to bottom but suddenly it guessed that it had to turn up in order to support the equation so it rolled up and formed the desired image :D :D :D rays are smart you see :))))

[@seanki98]

fakhruddin hussain what do you mean? ye it would be straight in real life but remember he is drawing freehand. if you are saying he cheated, that is not the case as we know from symmetry that this third ray and the one directly below it have to meet. A ray coming from the top of the object through the principal axis and the ray passing through the focal point have to meet: it works if you reverse it. Not so sure about the other ray so much. I mean if that ray has to meet with the middle ray then clearly it must meet with the first ray too. Hope that helps :)

[@seanki98]

al lool

[@martinthorne8979]

Excellent stuff and thank you for all your hard work - my students definitely benefit from this. But just one comment on this particular video - at about 28 minutes you show the curvature of the secondary mirror in a Cassegrain telescope as being concave, whereas I think it should be convex (spherical or hyperbolic apparently). The fitst edition of the CGP revision book got this wrong too. One of the Unit 5 AQA Examiners' reports commented on this so it's worth getting it right- they will be looking out for it.

[@DrPhysicsA]

Martin Thorne Many thanks for your kind words. And thanks for drawing my attention to the proper design of the Cassegrain telescope. I have added an annotation to correct this.

[@hifellow]

Dear Sir - I have always been confused regarding the parallel light rays entering the objective lens of the telescope and focusing to a point as depicted by a drawing. Are the source of these parallel light rays considered from a "point" on the object (e.g. moon) or are they light rays from different points on the object (different extents)? I very much enjoy your derivations and explanation! Thank You!

[@DrPhysicsA]

Each point on the object will reach a focus on the image. Different points on the object will reach different points on the image.

[@fablife55]

What is interference ? Do you have a video on it sir?

[@colossalko]

I remember going over this in physics.

[@comprehensiveboy]

Well they are both about vibrations, hopefully 'good vibrations'.

[@fablife55]

Thankyou so much ! :)

[@comprehensiveboy]

Are you also an entertainer?

[@jeeadvanced2024]

What is your name

[@08mitchellr]

sounds like bruce forsyth

[@jeeadvanced2024]

What is your email