Symmetry I

[@chaithanyaagurunathan4542]

crystallography was a boring subject to me until I found your lectures thanks a lot sir!!!!!!

[@purvakadwe6875]

Your teaching is too great sir!! I like the way of your teaching.

[@avinashrandive3415]

Thank you so much sir for going in so deep and at micro level. A lot of new learnings for me.. beautifully presented..

[@vikaschan9566]

excellent easiest way to to describe a crystal system. Thanks a lot for your great work sir.🎉

[@JobayerJisan]

what a beatiful way of teaching! long live sir.

[@KartikeyaDutta]

Sir you are an excellent lecturer.

[@pramodsakharkar7065]

excellent explanation for students , , with vivid clarification.

[@thelegend7406]

गुरू गोविन्द दोऊ खड़े, काके लागूं पांय। बलिहारी गुरू अपने गोविन्द दियो बताय।।

[@02abhinabamaity13]

Great teaching sir, thanks a lot.

[@kaushik8318]

Thank you very much sir, superb explanation....

[@venkatesh2993]

Sir your teaching is excellent get knowledge in subject.y u can take some other branch in physics like modern physics,electrostatics,etc i saw u r teaching in crystal growth .u r teaching is very good .

[@yarabanda9639]

Venkatesh where are the crystal growth videos?

[@v-movies4214]

kash aisa nit jamshedpur me padhaya jata

[@motiontv3621]

Kon sa year me ho bhai

[@EpicBlendUniverse]

Really great sir clear and clean explanation for starting students nd for all

[@priyambadaaiswarya1831]

How symmetry changes from one crystal structure to another crystal structure?

[@AnuvabAhmedApurno]

Again Awesome explanation. But, quasi-crystals can occur with 5-fold symmetries; these were not discovered until 1982 by Dan Shechtman. He won Nobel Prize for discovering quasi-crystals in 2011.

[@introductiontomaterialsscience]

But they do not have translational periodicity. Thus they can have noncrystallographic symmetry.

[@AnuvabAhmedApurno]

@@introductiontomaterialsscience Good point. That is why they are called the quasi-crystals. How about you make a lecture on quasi-crystals?

[@redduck7869]

hocam sağolun var olun ingilizceye saygı duymadığım için türkçe yorumumu yapıp gidiyorum elinize sağlık

[@Summer69384]

Bro😂😂😂

[@zainabm.s513]

Are these lectures based on (Materials Science and Engineering) by William D. Callister?

[@introductiontomaterialsscience]

No, not really. Callister does not emphasize symmetry in the discussion of crystallography.

[@zainabm.s513]

@@introductiontomaterialsscience Thanks for these great lectures

[@monishreddy1797]

sir if we rotate A by 180 along the y axis then it satisfies the 2 fold symmetry..So A has a 2 fold symmetry

[@maija6099]

Yes.

[@jaigogapeer2307]

Sir which book do you prefer???

[@ajayjoshi9256]

Sir, does these n values have anything to do with shape of unit cell?? i mean does this mean that a pentagon unit cell is not possible as it does not possess symmetry, and unit cell of other shape are possible?? thank you .

[@somyasahoo147]

Sir which book to refer for crystallography?

[@mr.chindo8570]

Sir in rotation symmetry, the motion or translation is about the axis.... I couldn't get translation in reflection and inversion symmetry and also how is it different from the rotational. Can someone please explain this to me.

[@introductiontomaterialsscience]

Just like rotation is about an axis, reflection is about a plane and inversion is through a point. Rotation is a physically possible motion. Reflection and inversion are only possible in imagination. Is that what is trobling you?

[@mr.chindo8570]

@@introductiontomaterialsscience I understood what you mean now.. thank you for taking the time to reply... I have seen almost the entire course multiple times... this course is slowly becoming like the Mahabharata Epic. I watch again and again and new meanings evolve. thank you, sir....

[@real7558]

But 1 fold symmetry means no symmetry then why it is compatible with crystallography restrictions

[@introductiontomaterialsscience]

1-fold means no rotational symmetry. It is possible to have a crystal with only translational symmetry and no rotational symmetry. Therefore, 1-fold is allowed for crystals.

[@real7558]

@@introductiontomaterialsscience thanku sir

[@pistonhead05]

I didn't understand the crystallographic restriction theorem, although great teaching.

[@introductiontomaterialsscience]

I have not provided any proof of the theorem here. Just stated it.

[@pistonhead05]

@@introductiontomaterialsscience I searched for this in Google, now I know why 5-fold is not applicable, thanks.

[@tapashreedas6074]

By 360 rotation everything comes into self coincidence then why n=1 is rotational assymetry did not understand!!!!!!

[@introductiontomaterialsscience]

Well, n=1 can be considered zero of symmetry. Rather than saying that an object has no rotational symmetry you can say that it has n=1 rotational symmetry.

[@tapashreedas6074]

@@introductiontomaterialsscience thank u sir

[@mr.chindo8570]

Sir, you said we will not prove why crystallographic restrictions have only 5 types of rotational axis... So you mean mathematically there is a proof for this?

[@introductiontomaterialsscience]

Yes indeed there is proof, and it is not a very difficult one. I usually do not teach it in my classroom course, so I left it out. You can google it.

[@mr.chindo8570]

@@introductiontomaterialsscience indeed I googled it sir. Fascinating. Although from the outside an atom looks like a physical concept but at the same time how mathematical can it be.. just mind-blowing..

[@jayakrishnaadapa8842]

Sir how can we say translational symmetry when some points are left with out coincidence

[@introductiontomaterialsscience]

No points should be left without coincidence in an ideal infinite crystal.

[@BC-yr6eg]

👍🏻👍🏻👍🏻👍🏻👍🏻

[@BC-yr6eg]

😀😀😀

[@prasannakumar5162]

sir aap padha nahi pa rhe hai...

[@introductiontomaterialsscience]

Aisa kyon bol rahe ho? Jara samjha kar bolo. Agii baar improve karne ki koshish karoonga.

[@himabindu8185]

Sir your just awesome

[@PrateekSharma016]

@@introductiontomaterialsscience arey sir mast padha rahe ho, iski mat suno. pranam gurudev

[@motiontv3621]

He came here after drunk. Sir taught excellent, first you need to understand then comments.