Does light refract on normal incidence?
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- เผยแพร่เมื่อ 11 ส.ค. 2022
- For normal incidence, Professsor H.C. Verma says refraction happens. I think it doesn't!
Here is the link to Professor's video.
• REFRACTION OR NO REFRA...
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Thnak You Mahesh, for this video. This video kind of changed my perspective a little, about Science(in general), and Physics(to be particular), that how certain definitions can be open to interpretation.
So true.
Thanks for acknowledging me, Anik!
I think more than the ultimate conclusion, it's the thinking process that matters!
I really like the expressions you make while conveying your arguments ;-)
Oh, thanks :D
I was in one of the classrooms you taught about 8 years ago. What I do now is not really physics related but I still sat and watched through your video.
Its proof of how interesting and engaging your classes were/are. Thank you.
Oh wow, your name?
@@Mahesh_Shenoy Rahul
I agree with the professor on this. If it has refractive index (which defines the speed change) it should be refracting when traveling at 90° angle into the medium. It refracts at 89.9999° and 90.0001° angles and 90° is not the limit and refraction neat 90° (= limit) should then be infinite. So if it does not refract at 90° it only does not refract at deltaFi = 0, so only in theory. We can only say it is not refracting at 0° angle as it does not travel through the medium.
then i would also counter argue, that what happens if the refractive index of a medium is 1 , then definitely it is the same medium as air and light does not bend and also don't change its speed and we don't call it as refraction , but what happens if refractive index is 1.00001 , then it changes the medium and refract right and speed changes , so the limit approaches 1 , so the same way as your argument i would counter argue that even in same medium light undergoes infinite refraction due to the change in the infinitesimal refractive index....
@@REVIEWSGALATTA I am not sure I understand you completely when you say "the limit approaches 1". Refractive index: n = c/v. Refraction: n1 * sin(θ1) = n2 * sin(θ2). Refraction is a redirection of a wave.
Never thought of definitions and word origins this way.
Neither did I. So much rich conversations we can have around something as mundane as the definition of refraction! I loved making this video!
Great!
Checked your video and realized that refract= re(again)+fract(the prefix or suffix 'fract' has a latin root which means 'to break').
Yup! That's the origin!
Isn’t there an infinitesimal phase shift at the border of the material from the same effect that causes refraction?
Hi Mahesh, can you do a video explanating what's an electromagnetic wave.
Hey but in earlier video you told that the speed of light never changes in any medium ?
Brother, I appreciate your understanding; please clarify few questions. What is name of the ray which is passing normally inside the glass surface? 2. Name the physical phenomenon which causes the change in speed of light when a ray of light is passing NORMALLY from one medium to another? 3.Why there is no exception/exclusion in 1st law of refraction of light for normal incidence? 4. What is called refracted ray?
Wow, love the questions buddy. That's an incredible way to critique and refute my argument. And just for those well thought, well constructed, well targeted specific questions, please take a bow, sir!
On the questions per say, here's how I think. Typically, for every angle other than zero, the change in speed of light causes bending. So, it makes sense to try and associate change in speed of light to refraction itself.
But my argument mostly comes from the etymology of the word.
Also, let me attempt to answer your questinos
1. Transmitted ray. :P
2. Transmission of light
3. Snell's original law is stated as Sin (i)/Sin (r) is a constant. for i =0, this gives you a zero by zero error. (This actually works in favour of my argument). You may modify the formula to say n1 Sin(i) = n2 Sin (r), but then that's how we define Snell's law.
4. Refracted ray is the transmitted ray that bends.
Sir Why do we take the ratio of "Sine" of angle of incidence and refraction?And why not the angles and what is special with this "Sine" why not Cosine or tan or something else?? In Snell's Law of refraction.
2:12 don't worry i never mind 😅😅
That was so spontaneous, I thought of editing it out, but then decided to just keep it!!!
@@Mahesh_Shenoy I am glad you did :P
Few min ago i watched H.C verma lecture video of refraction and i was completely disagreed and more than half of the video taught me wrong and now watching u r video i realised there is no refraction at 90 degree....thank you so much😊👍👍
I have another argument.
We say RI = sin i / sin r
Assume we experimentally found (by measuring speed) RI (of two materials)= 1.4
But when i = r = 90 ie light is perpendicular to the surface and goes in a straight line,
sin i/ sin r = 1 not = 1.4
We can say that in this case, the RI we found was not actually a "refractive" index but just a speed ratio.
Since sin i/ sin r != c/v we can say that no refraction has taken place. Just the speed changed.
Well if the light went straight, is it acurate to say it changed media?
@@Mahesh_Shenoy Actually I meant light falls perpendicular on the surface and goes straight (the example Verma sir was explaining)
what if the bending is exactly in the opposite direction? A complete 180 degree? Something similar to reflection but not really reflecting but absorption. Maybe this absorption is related to reduction in the speed of light. Just a thought
Why complicate things?
I watched your videos on khan academy india and trust me you are as good as albert einstein at physics , atleast that's what i think about you. From now on , i dont really give a shit about the marks i score , I'm just going to watch your videos for physics and just understand everything.
Wow, thanks! You mean Khan Academy India, right? :)
Yes khan academy india, i just edited .
How do you teach so good ? After listening to all the rubbish i am taught at school , all i know is to derive formulas and stuff , even if i ask doubts to my teacher, she just reads what's in the textbook and that is all . I genuinely smile while watching your videos , you know why ? It's because u make topics which i thought was difficult , much simpler and understandable . Thanks a lot Mahesh!! You have no idea how much you're helping me.
The magnetism video is not showing at last
Coming soon :D!
ok so if the velocity changes so does the wavelength to meet the conservation of energy. so why isn't the light in the water now a UV wavelength. I mean if you put blue light in you'd be able to generate sterilizing 268nm light from a 400nm normal incident beam. The transmission of the light through the clean water discounting scatter would not match the absorbance of the UV light in water when you look at what comes back out the other side of the water. Now with enough energy you can make a continuum through non linear effects but at lower threshold intensities why is this not observed? I have a headache
2:13 Damn, that made me laugh out loud XD
Same
Why did he skip it 😂
2:12 hahaha
fract can be break in medium rather than bend in light
That's a great point! We need to dig deeper into the etymology then!
Can you help us get to the bottom of this? :D
Or break the beam into the components (red, green, blue).
Read full defination of google
I think saying that "the light isn't retracting and just slowing down" is the same as saying "a 180 degree angle doesn't exist and is just a straight line." I think you are "putting the cart before the horse" (or the definition before the phenomenon). If angle was defined as something like the bending of a line, then people could argue that 180-degree angles don't exist because the line isn't bending, like how angle is defined. I think that this is still part of the refraction phenomenon, even though there is no bending of light. I believe the definition of refraction should be modified to account for this.
Angle is NOT defined as bending of line, but refraction literally means bending of light!
@@Mahesh_Shenoy
Thanks for replying to my comment!
I know thats not the definition of an angle; it was a hypothetical definition to illustrate how fitting a phenomenon to a bad definition causes problems, and I came up with that definition because it is similar to this situation, where excluding one specific instance (180-degree angle in the hypothetical and normal incidence here), despite its mechanism/behavior unchanging, is a bad idea and should have its definition changed to match the phenomenon or create a new term for it that encompasses the phenomenon in its entirety. (I.e. an umbrella term for both refraction and transmission).
But, I also have some more thoughts/counter-arguments:
1. Refraction means breaking of light, and I believe you could argue that a phase shift (slowing light) could count as breaking light.
2. I would argue that, in some sense, changing direction to the same direction is still a change in direction. Suppose I had an arrow and a button, and pressing the button makes the arrow point to a random direction. If I press the button and its random angle happens to be the same angle as it was before, I would still say it committed an angle change, but the net effect was nothing happened. In a similar manner, I would say passing through a medium is still causing an angle change, but to the same direction.
2:12 LMFAO
There's no video you're pointing to at the end. That's a book 😂
8:49 I know where this is going. Exited for your next video...
Haha! Me too
I love your explanation.
The earth IS flat, by the way.