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 .
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 .
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.
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.
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?
@@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....
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 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..
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.
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.
crystallography was a boring subject to me until I found your lectures thanks a lot sir!!!!!!
Your teaching is too great sir!! I like the way of your teaching.
Thank you so much sir for going in so deep and at micro level. A lot of new learnings for me.. beautifully presented..
Sir you are an excellent lecturer.
excellent explanation for students , , with vivid clarification.
excellent easiest way to to describe a crystal system. Thanks a lot for your great work sir.🎉
what a beatiful way of teaching! long live sir.
Great teaching sir, thanks a lot.
Thank you very much sir, superb explanation....
गुरू गोविन्द दोऊ खड़े, काके लागूं पांय।
बलिहारी गुरू अपने गोविन्द दियो बताय।।
Really great sir clear and clean explanation for starting students nd for all
How symmetry changes from one crystal structure to another crystal structure?
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 .
Venkatesh where are the crystal growth videos?
kash aisa nit jamshedpur me padhaya jata
Kon sa year me ho bhai
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 .
Sir which book to refer for crystallography?
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
Yes.
Are these lectures based on (Materials Science
and Engineering) by William D. Callister?
No, not really. Callister does not emphasize symmetry in the discussion of crystallography.
@@introductiontomaterialsscience
Thanks for these great lectures
Sir which book do you prefer???
👍🏻👍🏻👍🏻👍🏻👍🏻
Sir how can we say translational symmetry when some points are left with out coincidence
No points should be left without coincidence in an ideal infinite crystal.
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.
But they do not have translational periodicity. Thus they can have noncrystallographic symmetry.
@@introductiontomaterialsscience Good point. That is why they are called the quasi-crystals. How about you make a lecture on quasi-crystals?
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.
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?
@@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....
hocam sağolun var olun ingilizceye saygı duymadığım için türkçe yorumumu yapıp gidiyorum elinize sağlık
Bro😂😂😂
I didn't understand the crystallographic restriction theorem, although great teaching.
I have not provided any proof of the theorem here. Just stated it.
@@introductiontomaterialsscience I searched for this in Google, now I know why 5-fold is not applicable, thanks.
😀😀😀
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?
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.
@@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..
By 360 rotation everything comes into self coincidence then why n=1 is rotational assymetry did not understand!!!!!!
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.
@@introductiontomaterialsscience thank u sir
But 1 fold symmetry means no symmetry then why it is compatible with crystallography restrictions
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.
@@introductiontomaterialsscience thanku sir
sir aap padha nahi pa rhe hai...
Aisa kyon bol rahe ho? Jara samjha kar bolo. Agii baar improve karne ki koshish karoonga.
Sir your just awesome
@@introductiontomaterialsscience arey sir mast padha rahe ho, iski mat suno. pranam
gurudev
He came here after drunk.
Sir taught excellent, first you need to understand then comments.