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?
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
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, 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?
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 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.
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 , 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
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
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 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.
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 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 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
For a detailed explanation. you can subscribe to this channel:- th-cam.com/users/physicsvideo विस्तृत विवरण के लिए। आप इस चैनल को सब्सक्राइब कर सकते हैं: th-cam.com/users/physicsvideo
Sir you have applied Snell law here but here refraction isn't taking place instead reflection of the light is taking place here. So why have you applied Snell law here?
Snells law is applicable for even reflection.. I dont know if it is written in any books or not.. But n2/n1=sini/sinr... Now, n2=n1 for reflection Therefore, sini=sinr i=r
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?...
@@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. When we don't neglect the X^2 term and integrate . The equation we get takes only +ve values of Y. So it tells nothing about what happens after the point (0,0). Also it doesn't give two values of Y for single value of X
As you can see, Prof H C Verma has taken vertical as the x axis. Suppose we take upward direction as the positive x axis. When the light ray is going down, then it is moving in the negative x direction. When it is going up, then it is moving in the positive x direction. Therefore, you have to solve the problem in two parts - one for the light ray going down and the other for the light ray going up. You will get one equation for x < 0 and the other for x > 0. If you plot them, you will get two curves. You will find that these two curves are symmetric with respect to the x axis.
@@sadiqueabdullah574 and it is explained that it will not bend continuesly to to make parabolic path,but because of continues change in refractive index,it can bend continuesly.......
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.
Heat is a physical quantity and itself a form of energy. But certain heated objects emit electomagenetic radiations(called heat waves in this case) which is a mode of transfer of energy.
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, 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.
Bhai ese samjho 10000-15000 layers of air h... Usme har ek layer pichle layer se rarer h... So choti choti tareke se angle of refraction increases... Eise aur layers of air loge toh it will appear to be curved... Similar to integrating dx element
In simple words, Sir has considered critical angle to br 90° at "point" of turn which is only true if the two media have exactly same optical densities. So sir has considered the elemental(infinitesimal small) air-region at the point of turn, to have uniform optically density, but this is not exactly true bcz we know the air will be rearer below than above, though infinitesimally for elemental region, hence critical angle won't exactly be 90° which implies that at just before 90° TIR will indeed occur Also, i suppose, that the path won't be a perfect parabola🙄
Sir I agree with parabolic path for which nsina=constant but this is equally applicable If light go straight with making angle 90 degree because still nsina=constant there then why they change their path
Sir, as you said, from mathematical point of view it's okey that the light ray will follow Snell's law and curvature of the path will be parabolic. But I didn't get it why light will turn back (the actual physical phenomena that causes the light to bend?)?
It is a great explanation, Sir. But I would like to clarify two points. 1) When you say n sin (theta) is constant, then once the ray becomes horizontal it should stay such as n is not changing anymore thus theta should remain 90 for the rest of the path. It should not bend again. 2) Snell's law is valid as long as light is traveling from one medium to another of different optical densities. But once the ray becomes horizontal, it travels in the same medium. So can we use Snell's law at that boundary?
The catch is that TIR only occur at the lowest most point where incident ray becomes greater than critical angle which tends to be 90° as the ratio refractive index at that point and just below it is very minute, when you put it in calculator it comes out be like 0.999999. And when you take aSin of it you get critical angle about 89.8744°. Hence ray can only reflect by mechanism TIR after it has attained almost 90°. After reflecting a little, it again follws the parabolic pathway like it did to come to lowest most point.
Yes. the light ray moves horizontally but it bends upward a little because of wave nature of light. The speed of the upper part of a wavefront is lower than the speed of the lower part. Because of this the upper part travels smaller distance in a given time than the lower part. This causes a light beam to bend. In order to understand mirage, we cannot ignore the wave nature of light (not even as an approximation).
The theta in sin theta is not same as theta of tan theta at 7:35 because theta in tan theta is the angle made by tangent to the curve with x axis. Correct me if I am wrong please.
@@witscorpian bhai saab tan theta(which is wrong) is slope to the tangent of the curve at a point where tangent to curve makes angle of theta with a pine perpendicular to x axis. Slope is defined to be the tangent of the angle made by tangent to the curve with x axis. So slope of the tangent must be tan(90+theta)=cot theta.
@@manishk45 FIRSTLY feel your mind empty! Here tangent is instantaneous direction of light. Which makes an angle with X-axis ( Perpendicular to the atmospheric layers having different RI along Y-axis.) at any point of ray. According to snell's law; sine of angle between x-axis and tangent to the light ray multiplied by RI is constant everywhere on ray of light. dy/dx is slop of tangent which makes an angle theta with x-axis( Angle of refraction) i.e., sine of angle of refraction which will be multiplied by RI of that layer will be equal to RI at any given point of layer multiplied by sine of angle between tangent to the light ray and x-axis.
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Sir aapki video mil gyi toh bass .
Dhanye ho gye 🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏
सर जी आप बहुत महान है आप को कोटि कोटि नमन।
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 .
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
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
th-cam.com/video/s8MpL1NrxE0/w-d-xo.html
Mr Verma is god of physics for me.
Because Alakha sir follow verma sir .so for me he is legent of physics.....
Wow wowwww legend of physics❤🔥💚
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
Agathiya muni and Ayyanar Lord Muruga blessed prof.H.C.Verma.
🙏
@@TechnologyQuest369 Thank you sir.
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, 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?
Congratulation sir for padma shri
Boy question..10the level
Sirs answer ...😓😓😓
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 how far the actual object is from the place where mirage occured?
Agathiya muni prof.H.C.Verma always excels.
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.
Great
Y square = 4ax , has axis along x axis
Love from Bhagalpur ,Bihar sir aapke lectures bahut acche hain. Best Physics teacher .
Awesomely explained...Thank u sir....U just sweeped away my doubts...
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.
Bhai pura western science hi toh eastern scientists ne discover kia. Ese to sabka name change karna parega
Wrong
@@rishabhyadav6705 Would you care to explain what is wrong?
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
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
Very nice sir
Sir please tell about the eddy current....... And also what is reason behind it for only circulating current
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😍😍
Is it tan or cot?
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 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
Sir you are one of world's best teacher
It means TIR cause is wrong if it is wrong then how??
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.
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!?
Wow sir! Thank you so much.
Why are some objects opaque and some transparent?.
That 10th class student thinking what this differentiation and Integration is!😂 just kidding though!
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
For a detailed explanation. you can subscribe to this channel:- th-cam.com/users/physicsvideo
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Baba thanks
Sir you have applied Snell law here but here refraction isn't taking place instead reflection of the light is taking place here. So why have you applied Snell law here?
Snells law is applicable for even reflection.. I dont know if it is written in any books or not.. But n2/n1=sini/sinr...
Now, n2=n1 for reflection
Therefore, sini=sinr
i=r
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.
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 , 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.
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
Sir this is clear but why in desert we see a fake water like thing instead of image of a tree
Cloud's also undergo total internal reflection so we see clouds image(look like water) in ground
Very nice 👌 Sir, we proud of you to have such a great genius
Sir ,
with all due respect, can you please make a video on the transverse nature of light..
Thank you very much sir for explaining various topics on physics
Sir. When we don't neglect the X^2 term and integrate . The equation we get takes only +ve values of Y. So it tells nothing about what happens after the point (0,0). Also it doesn't give two values of Y for single value of X
As you can see, Prof H C Verma has taken vertical as the x axis. Suppose we take upward direction as the positive x axis.
When the light ray is going down, then it is moving in the negative x direction. When it is going up, then it is moving in the positive x direction. Therefore, you have to solve the problem in two parts - one for the light ray going down and the other for the light ray going up. You will get one equation for x < 0 and the other for x > 0. If you plot them, you will get two curves. You will find that these two curves are symmetric with respect to the x axis.
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.
Wow
Is it wrong that total internal reflection is the cause of mirage?
Not totally
It can be explained by snells law and even through TIR
thank you so much sir..i did'nt expect that practical at end...thank you so much..
apoorv rana
th-cam.com/video/s8MpL1NrxE0/w-d-xo.html
Awesome videos sir....really helpful...
I also have some doubts sir...how do I send them to you? please share mail id or some link
rip the kid of 10th class who asked the question!!
It’s in iit syllabus
@@prathamrevankar8266 nahi hai bro
Is it compulsory that angle of incidence has to be equal to 90°,it could be something else..........
mai bhi yahi soch raha ho??
@@sadiqueabdullah574 and it is explained that it will not bend continuesly to to make parabolic path,but because of continues change in refractive index,it can bend continuesly.......
exactly iska jawaab kya hai
yes, at some point to form mirage the ray has to tbe parallel to the bottom most layer and hence incident angle will be 90
Same question from one side
Sir i can ask a question?
Yes..
Sir I am radhe krishan kumar
Sir why are any object attract each other
Thanks sir
Sir apne to isse aur complex bana kar confuse kar diya mujhe 😅😅
Ab NCERT aasan lag rahi hai 😂
Amazing.
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 plz explain- heat is a form of energy or mode of transfer of energy- its still confusing
Heat is a physical quantity and itself a form of energy. But certain heated objects emit electomagenetic radiations(called heat waves in this case) which is a mode of transfer of energy.
Heat is a mode of transfer of energy.
Its bending can be explained by considering huygens principle i.e each point on wavefront behaves like point source.
The experiment is great....
Thanks ...Sir
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, 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.
Will the incident angle at O always be 90 degree?
Haliday resnik does not say mirage.
Wikipedia does not say mirage
Sir please make a video for class 10 all chapter of physics in deeply sir please make video
Plz sim make all video jee advance and jee mains
Sir, do it also concludes that light doesn't follow rectilinear propagation ?
No light bends learn about refraction
Yes....In ray optics,we consider rectilinear propagation of light.....
Rectilinear propagation in homogeneous isotropic medium me follow hota hai
Bhai ese samjho 10000-15000 layers of air h... Usme har ek layer pichle layer se rarer h... So choti choti tareke se angle of refraction increases... Eise aur layers of air loge toh it will appear to be curved... Similar to integrating dx element
i like your teaching style so muchhh
Legend get to know about TIR in 12th😂
thank you sir this vid helped me a lot :)
In simple words,
Sir has considered critical angle to br 90° at "point" of turn which is only true if the two media have exactly same optical densities.
So sir has considered the elemental(infinitesimal small) air-region at the point of turn, to have uniform optically density, but this is not exactly true bcz we know the air will be rearer below than above, though infinitesimally for elemental region, hence critical angle won't exactly be 90° which implies that at just before 90° TIR will indeed occur
Also, i suppose, that the path won't be a perfect parabola🙄
4:47 in this how nsin theta is equal to constant.
Sir its it's akshat of class 12 maths and my concern is why does the magnetic force appears in nature
Why did YOU appear in nature,=-O :-D 😹😹
stationary charges create electric field , moving charge creates magnetic field, accelerating charge creates electromagnetic field..
Actually their is no real example of internal reflection, because their is a part of refraction also.
Sir the angle is measured relative to perpendicular but why sir ? We can take the incident ray making an angle with surface rather than with normal
Incident, refrecive ray and normal are always lies in same plane
Sir I agree with parabolic path for which nsina=constant but this is equally applicable If light go straight with making angle 90 degree because still nsina=constant there then why they change their path
Sir, as you said, from mathematical point of view it's okey that the light ray will follow Snell's law and curvature of the path will be parabolic. But I didn't get it why light will turn back (the actual physical phenomena that causes the light to bend?)?
It's Total internal reflection only
for image formation atleast two rays are needed
but no one draws to rays to explain
It is a great explanation, Sir. But I would like to clarify two points.
1) When you say n sin (theta) is constant, then once the ray becomes horizontal it should stay such as n is not changing anymore thus theta should remain 90 for the rest of the path. It should not bend again.
2) Snell's law is valid as long as light is traveling from one medium to another of different optical densities. But once the ray becomes horizontal, it travels in the same medium. So can we use Snell's law at that boundary?
The catch is that TIR only occur at the lowest most point where incident ray becomes greater than critical angle which tends to be 90° as the ratio refractive index at that point and just below it is very minute, when you put it in calculator it comes out be like 0.999999. And when you take aSin of it you get critical angle about 89.8744°. Hence ray can only reflect by mechanism TIR after it has attained almost 90°. After reflecting a little, it again follws the parabolic pathway like it did to come to lowest most point.
Yes. the light ray moves horizontally but it bends upward a little because of wave nature of light. The speed of the upper part of a wavefront is lower than the speed of the lower part. Because of this the upper part travels smaller distance in a given time than the lower part. This causes a light beam to bend.
In order to understand mirage, we cannot ignore the wave nature of light (not even as an approximation).
Where I can ask questions from you
You can gmail your question on this email hcverma@iitk.ac
@@nikhildhania5021 thanks
Beautiful explanation...!!
Sir,why the light Ray travel from rarer to dense towards the normal and denser to rarer away from normal?
please tell me about "dual nature of light" and what are the causes for this in the view of quantum physics.
Not only light have dual nature all object shows dual nature when they achieve the speed comparable to speed of light
@@naveenjaiswal5939 that's not true mate.
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
Sir, I am Sovan Mondal, a student of class 12. I have a question. Is a 10^6Ω carbon resistor's colour code Black, Brown, Blue?
Hey dude
Sir ,please make a video on lagrangian mechanics.
Yes Sir, we need it
Yup
Yesss the proofwork specifically
The theta in sin theta is not same as theta of tan theta at 7:35 because theta in tan theta is the angle made by tangent to the curve with x axis.
Correct me if I am wrong please.
Both are angles made by ray with perpendicular on the same horizontal layer or different horizontal layers.
@@witscorpian bhai saab tan theta(which is wrong) is slope to the tangent of the curve at a point where tangent to curve makes angle of theta with a pine perpendicular to x axis. Slope is defined to be the tangent of the angle made by tangent to the curve with x axis. So slope of the tangent must be tan(90+theta)=cot theta.
@@manishk45 FIRSTLY feel your mind empty! Here tangent is instantaneous direction of light. Which makes an angle with X-axis ( Perpendicular to the atmospheric layers having different RI along Y-axis.) at any point of ray. According to snell's law; sine of angle between x-axis and tangent to the light ray multiplied by RI is constant everywhere on ray of light. dy/dx is slop of tangent which makes an angle theta with x-axis( Angle of refraction) i.e., sine of angle of refraction which will be multiplied by RI of that layer will be equal to RI at any given point of layer multiplied by sine of angle between tangent to the light ray and x-axis.
@@witscorpian Oh i got it, i didn't noticed that he has taken x axis as perpendicular and y axis as horizontal line. Thanx bhai
@@manishk45 it's ok! Don't doubt upon him. He is one of the best teachers.
90 at the bottom is not necessay, it has to be just greater than critical angle, so I think Sir has got this wrong, please check my proposition