NCERT is not written by a single physicist but it has been written by many physicists........ So they what to give and what level should b given to students.....
I think two rectification is needed to think in right direction. 1 The angle of incidence is not exactly 90degree but very close to 90 degree 2.considering the layer of atmoshpheric layer at micro level .then the confusion of TIR will be solved .TIR happen but with very large angles close to 90degree.then his concept of bending is right .the ultimate trajectory will be parabola symmetrical to x axis .
Sir sorry to say but u did not talk about the bending back of light at the vertex of the parabolic path. I think that if we are considering the refractive index to be changing gradually, then the ratio of refractive indices of two consecutive elemental layers will be close to 1. So if anywhere in this setup, Total Internal Reflection (TIR) has to happen, by snells law we can find that critical angle C = sin^-1 (n2/n1) where light is going from medium with refractive index n1 to medium with n2. As I've said earlier, since the variation in refractive index between two consecutive elemental layers will be very less, the ratio n2/n1 will tend to 1 ( a little less than one actually) . So critical angle C will tend to 90° (a little less than 90°actually). That means, if anywhere in this setup, TIR happens, it will happen only when incidence angle tends to 90°. So as u explained, initially only refraction will happen and the first half of the parabolic trajectory will be there. But then at the vertex, as soon as the tangent is about to become horizontal, the angle of incidence will tend to 90° and so TIR will happen. That's why light ray should bend up again JUST BEFORE reaching the vertex. If light ray had reached vertex of parabola and had become horizontal once, then it would have always remained horizontal forever bcoz there is no change in refractive index horizontally The method u used can help us find the trajectory of the part where REFRACTION is happening, but the light ray will bend up only bcoz of TIR, that's what I concluded. Am I correct?
I want to make a humble point here! Both your method and total internal reflection method are correct. Your method explains why it has to bend, theoretically. TIR method tells how it bends, practically. So both are correct. The question of incident angle being 90deg has no meaning. Because in that case, the light ray is not touching surface at all. Also there's no need for the ray to get until 90deg to get totally reflected. So from my point of view, both styles of explanation are correct. If anybody has another point of view, we can discuss here 😊
No...sir is ryt... Total internal reflection is not the cause here...because tir occurs when there is sharp difference in refractive index between two layers which is not the case here. ... Don't be oversmart.... Being curious is good but first try to understand what sir is saying
@@thecomedian9077 Don't get offended brother! Stay calm please! I'm not saying he is wrong. He is correct! But meanwhile TIR is also correct. That's my statement. Have you ever heard of index gradient reflection?! Normally, TIR refers to reflection at an interface between a high index material and a low index material. "index gradient reflection" occurs without need for an interface: instead, it requires only a refractive index that changes gradually. The light rays never need to encounter an interface where the index changes abruptly. Please read my first comment carefully once again. I hope I had a point. I may be wrong. But we can discuss on it with proofs. Thanks for the healthy discussion😍👍
If we assume that refractive index is continuously changing, then TIR cannot be correct. Here is why TIR says that there is some critical angle (let us say angle C) such that when angle of incidence is greater than C, then the light ray will not go into the second medium but will be fully reflected back into the first medium. As you can see here, the value of C must be less than 90 degree because angle of incidence has to be less than 90 deg. When refractive index changes continuously, then even if you take angle of incidence as 89.99 deg or any value less than 90 deg, there will not be reflection. So what will you take as the value of C? The light ray continuously bends till the angle of incidence becomes 90 degree. After that it moves up due to Huygen's principle (each point acts like a wave front). Then again it keeps on bending as it moves up.
@@thecomedian9077 how can you think , refractive indices of air are continuously distributed ,,Verma sir case ,is not actually what going on.,and without TIR Mirage not possible,,the relationship btw deviation and incident rays in his book is parabolic for a certain domain because refractive index is smooth.
@@ABCDAnyBodyCanDo sir ne practical bhi diya last me tir can happen only when there are 2 media involved , But air has technically lots o media(wiith varying n)
Sir what if refractive index of air is not linearly increasing and there is no any critical point at the time of refraction and angle of incidence suddenly become greater than critical angle and the reflection occur
For a detailed explanation. you can subscribe to this channel:- ua-cam.com/users/physicsvideo विस्तृत विवरण के लिए। आप इस चैनल को सब्सक्राइब कर सकते हैं: ua-cam.com/users/physicsvideo
The law of refraction was discovered by the Arabic scientist Ibn Sahl in 984 AD. Snell wrote down the equation in 1621 AD. Earlier we did not know about Ibn Sahl so credit was given to Snell. But now that we know Ibn Sahl found the law more than 500 years earlier, it should properly be called Ibn Sahl's law. Look at the Wikipedia article on Ibn Sahl.
Sir, would have been better if you would have explained wheres the fault in TIR explanation and why have you assumed gradual variation of refractive index is linear?
If there is parabola, vertex is one point.So,the incidence angle must be less than 90 degree &greater than critical angle.So,it is formed due to the reason for TIR.Hope,this comment,HC Verma sir will see and reply.I respect him very much
Maybe this is a little bit late but anyways here's my opinion Sir as you know the axis that HC verma sir has taken to be tangent of parabola is y axis and the axis of parabola is x axis i.e it is normal at the vertex and we also know that the y axis is perpendicular to the x axis so the angle of incidence is 90°. Hope it helps
Sir with due respect it will still not explain the behaviour of the ray at the vertex. I agree with the parabolic shape of the curve but why it bends is still unexplainable.
While the horizontal path at vertex satisfies Snell's law, it is not a stable path. Any perturbation in upward direction will result in further upwards bending, eventually causing the bent path as shown.
Sir , may be bending it light is due to internal reflection. as refractive index gradually decrease so reflected light is partially refractured and reflected when it fall on interfere of rarer and denser medium Refracted light shiws bending... I m
But can TIR be totally ruled out? Small deviation from critical angle is quite possible. Gradually increasing and then decreasing ( after reflection) angle of incidences will also make a light ray traverse a path. similar to a parabola.
Sir, I think angle of incidence 90° hone se pahle hi total internal reflection ho jayega isliye 90° vali situation nhi aayegi. Neeche se curve smooth nhi hoga
Sir due to curvature of space time continuum may we explain mirage phenomena? I think mirage actually accur due to variable space time with respect to x due to changing density. You say to keep n multiplied by sin theta constant the path of light follow that parabolic trajectory. Mathematics said that. I have no doubt about it. But if we consider here light is a collection of particle how we explain mirage phenomena? Which force is responsible here to bent the path of photon which have momentum? Please kindly reply sir.
Sir after total reflection the light again travels back from rarer to denser medium so it moves towards the normal while passing thru every layer so it apears that it bends
Respected sir, in rainbow formation total internal reflection involved or not . I found contradiction in concept of physics part 1 2012 print and foundation science physics for class 10. Forth adition reprint 2012. Regards Nitin nagar class 10th.
Great explanation sir....👏👏👏 With all due respect i want to say something.... I think this kind of explanation will not help to the students of class 10.
concepts are not according to some class or standard. may a class 10 student will understand this in class 11, but the concept of mirage remains the same.
@@shambhuyadav212 no. Both wavelength and speed changes. But the frequency remains constant. Speed of Light (in any medium) = frequency of the light wave multiplied with its wavelength.
Sir can't this be that their are infinite.interfaces as if we consider.dl^2 has one.interface then their will.be infinite interfaces so infinite lines will form.a curve...therefore the curve can be explained by tir
Sir I have a doubt,that the actual curve of a mirage should not be a parabolic its just seems to like parabolic...if that is right then in that case how one can able to explain that mirage concept of using your this explanation where as your final result shows that curve should be like a parabolic curve!?
Sir I hope that as n is increasing, it may not increase as a linear function of x it may increase on the x^p here, where p is any positive real number?...
Sir, with due respect, I would request you to reconsider your explanation. You say, you have a problem at the vertex point in your diagram where i=90deg; Are you sure that incident rays are reaching 'your' vertex? Pls do consider that a few layers before your vertex, critical angle will be reached, where the rays will reflect AS WELL AS graze at your r=90. Real world (aka fluctiation in densities) may make your grazing rays rise up, but Mathematically they wont. If you say that the layer densities are so minutely changing that the index diff is very less and hence the critical angle is almost 90 deg; then too i will advise you to take help of REFLECTION to make your rays rise back. Btw then your calculated path will be very very close to the actual path (provided your proposed index variation is taken), but i know that you will know the big difference is the reasoning (i never reaches 90 deg). Btw i always tell my students, that refraction of a beam of light doesn't rule out reflection; reflection always happens; the only question is how much. To cut things short : If you consider parallel layers of varying densities, then a light ray going down can not come back upwards based on REFRACTION no matter what the refractive indices are. Only reflection can send the rays back. TIR WILL happen before i becomes 90deg. One may further note that the INTERNAL reflections happening before TIR will start superseding the intensity of refracted ray as the rays become more and more slant.
Very good morning dear sir , Just needed to mention that the output of differentiation obtained is incorrect and so wrong is the integration ' s output obtained . Even the correct output does not resembles to any sort of parabolic equation. It is = -1 -------------- a( (ax)^2 + 2axc )^1/2 Where a =alpha C = n subscript o
Sir aapki video mil gyi toh bass .
Dhanye ho gye 🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏
सर जी आप बहुत महान है आप को कोटि कोटि नमन।
Mr Verma is god of physics for me.
Because Alakha sir follow verma sir .so for me he is legent of physics.....
Absolutely satisfied, I wish ncert also update its book with your explanation for a mirage..
NCERT is not written by a single physicist but it has been written by many physicists........
So they what to give and what level should b given to students.....
Wo khabhi nahi ho sakhata
@@yasirshahmbbs level. Does level means to teach wrong
Haliday resnik does not say mirage.
Wikipedia does not say mirage.
Madhav University page also does not say mirage
@@Thephysicsplace Then what they say about this?
This is brilliant 👌
I think two rectification is needed to think in right direction. 1 The angle of incidence is not exactly 90degree but very close to 90 degree
2.considering the layer of atmoshpheric layer at micro level .then the confusion of TIR will be solved .TIR happen but with very large angles close to 90degree.then his concept of bending is right .the ultimate trajectory will be parabola symmetrical to x axis .
Wow wowwww legend of physics❤🔥💚
Sir sorry to say but u did not talk about the bending back of light at the vertex of the parabolic path.
I think that if we are considering the refractive index to be changing gradually, then the ratio of refractive indices of two consecutive elemental layers will be close to 1. So if anywhere in this setup, Total Internal Reflection (TIR) has to happen, by snells law we can find that critical angle C = sin^-1 (n2/n1) where light is going from medium with refractive index n1 to medium with n2. As I've said earlier, since the variation in refractive index between two consecutive elemental layers will be very less, the ratio n2/n1 will tend to 1 ( a little less than one actually) . So critical angle C will tend to 90° (a little less than 90°actually). That means, if anywhere in this setup, TIR happens, it will happen only when incidence angle tends to 90°.
So as u explained, initially only refraction will happen and the first half of the parabolic trajectory will be there. But then at the vertex, as soon as the tangent is about to become horizontal, the angle of incidence will tend to 90° and so TIR will happen. That's why light ray should bend up again JUST BEFORE reaching the vertex. If light ray had reached vertex of parabola and had become horizontal once, then it would have always remained horizontal forever bcoz there is no change in refractive index horizontally
The method u used can help us find the trajectory of the part where REFRACTION is happening, but the light ray will bend up only bcoz of TIR, that's what I concluded.
Am I correct?
Guru mujhe tuition padha dijye🤯🤯
@@drjkbkgk826 teko bhi aajaye ga bass iit crack kar le aur mathematics mai phd 😂
Ya bro you are correct somewhat
I think same
You are wrong
@@arunsaha5970 please explain how
Congratulation sir for padma shri
I want to make a humble point here! Both your method and total internal reflection method are correct. Your method explains why it has to bend, theoretically. TIR method tells how it bends, practically. So both are correct. The question of incident angle being 90deg has no meaning. Because in that case, the light ray is not touching surface at all. Also there's no need for the ray to get until 90deg to get totally reflected. So from my point of view, both styles of explanation are correct. If anybody has another point of view, we can discuss here 😊
No...sir is ryt... Total internal reflection is not the cause here...because tir occurs when there is sharp difference in refractive index between two layers which is not the case here. ... Don't be oversmart.... Being curious is good but first try to understand what sir is saying
@@thecomedian9077 Don't get offended brother! Stay calm please! I'm not saying he is wrong. He is correct! But meanwhile TIR is also correct. That's my statement. Have you ever heard of index gradient reflection?! Normally, TIR refers to reflection at an interface between a high index material and a low index material. "index gradient reflection" occurs without need for an interface: instead, it requires only a refractive index that changes gradually. The light rays never need to encounter an interface where the index changes abruptly. Please read my first comment carefully once again. I hope I had a point. I may be wrong. But we can discuss on it with proofs. Thanks for the healthy discussion😍👍
If we assume that refractive index is continuously changing, then TIR cannot be correct. Here is why
TIR says that there is some critical angle (let us say angle C) such that when angle of incidence is greater than C, then the light ray will not go into the second medium but will be fully reflected back into the first medium.
As you can see here, the value of C must be less than 90 degree because angle of incidence has to be less than 90 deg.
When refractive index changes continuously, then even if you take angle of incidence as 89.99 deg or any value less than 90 deg, there will not be reflection. So what will you take as the value of C? The light ray continuously bends till the angle of incidence becomes 90 degree. After that it moves up due to Huygen's principle (each point acts like a wave front). Then again it keeps on bending as it moves up.
@@thecomedian9077 how can you think , refractive indices of air are continuously distributed ,,Verma sir case ,is not actually what going on.,and without TIR Mirage not possible,,the relationship btw deviation and incident rays in his book is parabolic for a certain domain because refractive index is smooth.
@@ABCDAnyBodyCanDo sir ne practical bhi diya last me tir can happen only when there are 2 media involved ,
But air has technically lots o media(wiith varying n)
Agathiya muni and Ayyanar Lord Muruga blessed prof.H.C.Verma.
🙏
@@TechnologyQuest369 Thank you sir.
Then sir fir q hume glt pdaya jata hai...... Aap iss chiz ko aage bdao aur apne name se iss chiz ko explain kro sir ...
DEEPAK MANDAL
ua-cam.com/video/s8MpL1NrxE0/v-deo.html
Love from Bhagalpur ,Bihar sir aapke lectures bahut acche hain. Best Physics teacher .
Agathiya muni prof.H.C.Verma always excels.
Awesomely explained...Thank u sir....U just sweeped away my doubts...
Great
Sir you are one of world's best teacher
Wow sir! Thank you so much.
i like your teaching style so muchhh
Baba thanks
Y square = 4ax , has axis along x axis
Very nice 👌 Sir, we proud of you to have such a great genius
Sir what if refractive index of air is not linearly increasing and there is no any critical point at the time of refraction and angle of incidence suddenly become greater than critical angle and the reflection occur
Boy question..10the level
Sirs answer ...😓😓😓
Very nice sir
For a detailed explanation. you can subscribe to this channel:- ua-cam.com/users/physicsvideo
विस्तृत विवरण के लिए। आप इस चैनल को सब्सक्राइब कर सकते हैं: ua-cam.com/users/physicsvideo
The law of refraction was discovered by the Arabic scientist Ibn Sahl in 984 AD. Snell wrote down the equation in 1621 AD. Earlier we did not know about Ibn Sahl so credit was given to Snell. But now that we know Ibn Sahl found the law more than 500 years earlier, it should properly be called Ibn Sahl's law. Look at the Wikipedia article on Ibn Sahl.
Wrong
@@rishabhyadav6705 Would you care to explain what is wrong?
The experiment is great....
Sir, would have been better if you would have explained wheres the fault in TIR explanation and why have you assumed gradual variation of refractive index is linear?
Wow
If there is parabola, vertex is one point.So,the incidence angle must be less than 90 degree &greater than critical angle.So,it is formed due to the reason for TIR.Hope,this comment,HC Verma sir will see and reply.I respect him very much
Maybe this is a little bit late but anyways here's my opinion
Sir as you know the axis that HC verma sir has taken to be tangent of parabola is y axis and the axis of parabola is x axis i.e it is normal at the vertex and we also know that the y axis is perpendicular to the x axis so the angle of incidence is 90°.
Hope it helps
Best part
Hum apni laboratory me mirage banayenge
Which is usually can't done in schools...
Thanks sir😍😍
Thanks sir
Thank you very much sir for explaining various topics on physics
Sir with due respect it will still not explain the behaviour of the ray at the vertex. I agree with the parabolic shape of the curve but why it bends is still unexplainable.
True. Because if n sin (theta) remains constant then when the ray becomes horizontal it should stay like that for the rest of the path.
While the horizontal path at vertex satisfies Snell's law, it is not a stable path. Any perturbation in upward direction will result in further upwards bending, eventually causing the bent path as shown.
It's bending is understood from the trajectory of any differential part of light ray...
Its bending can be explained by considering huygens principle i.e each point on wavefront behaves like point source.
Because the speed of light change with the change in medium due to the difference in the optical density of the media.
Thanks ...Sir
Thank you sir
Even I thought of a similar reason but in most of the books it was the wrong fact based on TIA
It was not wrong mam. Both the explanations are correct. TIR is a practical explanation whereas this is theoretical explanation.
Very nice doubt clearing class.
Awesome videos sir....really helpful...
Sir , may be bending it light is due to internal reflection. as refractive index gradually decrease so reflected light is partially refractured and reflected when it fall on interfere of rarer and denser medium
Refracted light shiws bending...
I m
Amazing.
But can TIR be totally ruled out?
Small deviation from critical angle is quite possible.
Gradually increasing and then decreasing ( after reflection) angle of incidences will also make a light ray traverse a path. similar to a parabola.
thank you so much sir..i did'nt expect that practical at end...thank you so much..
apoorv rana
ua-cam.com/video/s8MpL1NrxE0/v-deo.html
Sir you are man of humane
And your expression is full of simplicity
That 10th class student thinking what this differentiation and Integration is!😂 just kidding though!
Very good conseft.
thank you sir this vid helped me a lot :)
Sir please tell about the eddy current....... And also what is reason behind it for only circulating current
Awesome practical
Thank you sir this excellent explanation.
Sir how far the actual object is from the place where mirage occured?
Thanks a lot sir for great explanation of mirage. I read books for physics written by you. My dream come true watching you and clearing my doubt
Legend get to know about TIR in 12th😂
Sir, I think angle of incidence 90° hone se pahle hi total internal reflection ho jayega isliye 90° vali situation nhi aayegi.
Neeche se curve smooth nhi hoga
Vertex toh hoga hi parabola(curve) ka
Sir due to curvature of space time continuum may we explain mirage phenomena? I think mirage actually accur due to variable space time with respect to x due to changing density.
You say to keep n multiplied by sin theta constant the path of light follow that parabolic trajectory. Mathematics said that. I have no doubt about it. But if we consider here light is a collection of particle how we explain mirage phenomena? Which force is responsible here to bent the path of photon which have momentum? Please kindly reply sir.
please learn some real physics before asking such questions.
Thank you so much sir
Sir after total reflection the light again travels back from rarer to denser medium so it moves towards the normal while passing thru every layer so it apears that it bends
This is the understanding i had in my mind till today
Respected sir, in rainbow formation total internal reflection involved or not .
I found contradiction in concept of physics part 1 2012 print and foundation science physics for class 10. Forth adition reprint 2012.
Regards Nitin nagar class 10th.
It is not Tir...it is internal reflection that happens along with refraction
@@PrayaasPhysicsClassesDehradun new edition of hc Verma has corrected it
Is it tan or cot?
Its bending can be explained by considering huygens principle i.e each point on wavefront behaves like point source.
Great job
Plz sim make all video jee advance and jee mains
3 inch(1.5
Very easy to understand sir.
In simple words we can say
Yahan Kai bar ek hi direction me dhire dhire rays ka refraction hua hai .
am I right ?
Sir ,
with all due respect, can you please make a video on the transverse nature of light..
rip the kid of 10th class who asked the question!!
It’s in iit syllabus
@@prathamrevankar8266 nahi hai bro
Sir please make a video for class 10 all chapter of physics in deeply sir please make video
Beautiful explanation...!!
I am your great fan sir
Great explanation sir....👏👏👏
With all due respect i want to say something....
I think this kind of explanation will not help to the students of class 10.
Exactly
But I'm in 10th and it IS damn Helpful to me.
concepts are not according to some class or standard. may a class 10 student will understand this in class 11, but the concept of mirage remains the same.
Even in 12 CBSE boards we have to write the reason as T.I.R though it may be wrong
Right
Sir , but in the brachistocrome problem the path of light though a continuously variable refractive medium is a cycloid .
Yeah right
Maybe not neglecting alpha² x² leads to cycloid
the path isn't continously variable , the change in a small fraction is very small
Sir , when light comes in water from air then its wavelength change but the colour is not change. While different wavelengths have different colours.
wavelength never change s only speed changes
@@shambhuyadav212 no. Both wavelength and speed changes. But the frequency remains constant.
Speed of Light (in any medium) = frequency of the light wave multiplied with its wavelength.
*WOW !!!!*
Sir can't this be that their are infinite.interfaces as if we consider.dl^2 has one.interface then their will.be infinite interfaces so infinite lines will form.a curve...therefore the curve can be explained by tir
Why are some objects opaque and some transparent?.
Wonderful !!!
It means TIR cause is wrong if it is wrong then how??
Great teacher
Sir I have a doubt,that the actual curve of a mirage should not be a parabolic its just seems to like parabolic...if that is right then in that case how one can able to explain that mirage concept of using your this explanation where as your final result shows that curve should be like a parabolic curve!?
Thank you sir please make a video on relativity theory
Thanks a lot sir!!
Sir apne to isse aur complex bana kar confuse kar diya mujhe 😅😅
Ab NCERT aasan lag rahi hai 😂
Sir plz make videos for class 11 refering your book CONCEPTS OF PHYSICS
Alakh Pandey sir ka channel check kar lete
@@AdityaSingh-tg3pd he asked 2 years ago
Great great
Sir I hope that as n is increasing, it may not increase as a linear function of x it may increase on the x^p here, where p is any positive real number?...
See since Alpha is very small so we can consider linear variation
Even if it is varying some other way, if n is continuously varying, then ITR cannot be correct explanation for mirage.
Great sir.....
Sir, with due respect, I would request you to reconsider your explanation.
You say, you have a problem at the vertex point in your diagram where i=90deg; Are you sure that incident rays are reaching 'your' vertex?
Pls do consider that a few layers before your vertex, critical angle will be reached, where the rays will reflect AS WELL AS graze at your r=90. Real world (aka fluctiation in densities) may make your grazing rays rise up, but Mathematically they wont.
If you say that the layer densities are so minutely changing that the index diff is very less and hence the critical angle is almost 90 deg; then too i will advise you to take help of REFLECTION to make your rays rise back. Btw then your calculated path will be very very close to the actual path (provided your proposed index variation is taken), but i know that you will know the big difference is the reasoning (i never reaches 90 deg).
Btw i always tell my students, that refraction of a beam of light doesn't rule out reflection; reflection always happens; the only question is how much.
To cut things short : If you consider parallel layers of varying densities, then a light ray going down can not come back upwards based on REFRACTION no matter what the refractive indices are. Only reflection can send the rays back. TIR WILL happen before i becomes 90deg. One may further note that the INTERNAL reflections happening before TIR will start superseding the intensity of refracted ray as the rays become more and more slant.
Extraordinary Lecture...
He has missed √2
Very good morning dear sir ,
Just needed to mention that the output of differentiation obtained is incorrect and so wrong is the integration ' s output obtained .
Even the correct output does not resembles to any sort of parabolic equation.
It is
= -1
--------------
a( (ax)^2 + 2axc )^1/2
Where a =alpha
C = n subscript o
4:47 in this how nsin theta is equal to constant.
Thnq so much sir 🙏🙏🙏
sir just ausummmm . we can not think those wrong concept which we study many of times .
great explanation sir concept clear hay
for image formation atleast two rays are needed
but no one draws to rays to explain
nice sir
God of physics...kaash ye hmare physics k teacher hote skul me...to physics se pyar ho jata hme
Beautiful.
Sir absolutely nice
Haliday resnik does not say mirage.
Wikipedia does not say mirage
Sir, but why angle i= angle r ?
Angle r is angle of refraction, not reflection. As TIR is one type of refraction. ?
Any one please explain