@@Ayushmangarnaik738 Awesome question. Please watch my latest video on meaning on sign convention in physics. Its a 45 min long video and you will not only get answer to your question but also never have any doubt about positive and negative signs in physics.
Sir if pseudo force is imaginary and only experience by observer in non interial frame then why pendulum in a accelerating train appear to move backward by interial observer also
This is an excellent question! Alot of students get this doubt. The answer however is very simple. Suppose that the person is standing on ground and the train having a pendulum attached to its ceiling is at rest in front of him. Since the train is at rest , so the pendulum inside is also at rest. When the train suddenly starts accelerating , the body of the train moves ahead along with the point of suspension of the pendulum but the bob of the pendulum is not able to share the motion of the train immediately. Thus the body if the train moves ahead along with point of suspension but the bob is left behind and it appears as if the bob moves backward because of some force acting on it. In reality, the train moves ahead and bob lags behind and that gives us the observation
Sir can you please provide an example where there is bending of light and no change in medium. This example itself will be enough to prove that bending of light is not refraction but an inessential consequence of refraction. I hope u will see my comment🤞 Edit :- is it even possible that there is bending of light without the change in medium of propagation of light? I mean does light only bend when it travels from 1 medium (rarer) to another medium (denser) obliquely.
Good question!! See Bending means change in direction of propagation and it happens even during reflection isnt it? Some people feel bending happens only towards the normal or away from the normal , which is not the case. Conclusion: Reflection= returning of light into the same medium Refraction= Light entering another medium. Bending may or maynot happen in both the cases. So the answer to your question "Give an example where light bends without change in medium" will be reflection of light. I hope that answers your question
Sir i Googled this topic and the whole internet is filled with that bending of light when light travels from one medium to another obliquely. Now there are qus out there which ask - give condition when no refraction occur and they give answer that no refraction occurs when light travels perpendicular to the surface. Even school, coaching, har jagah yahi CHL rha even badi badi websites me bhi yahi dikha rahe. I study in aakash institute, vahan ke physics teacher ne bhi yahi kaha ki refraction tab nahin hota hai jab light perpendicular to the surface strike karta hai. Sir pls help karo🙏🙏🙏. Maine lagta hai jyada elaborate kardiya isliye in short qus yeh hai - Jis cheez ko aap misconception keh rahe hain wahi har jagah bataya ja rha hai. It feels like u are challenging the whole physics world.
@@lalitadevi365 I appreciate your enthusiasm for physics and your research. Dont worry , I will answer each one of your questions. First let me tell you where I am coming from and why have I made this video. 1. It is clearly mentioned in Fundamental of Physics , by Resnik Halliday Walker (which is one of the most authentic sources of physics) where the author says and I quote "The travel of light through a surface (or interface) that separates two media is called refraction, and the light is said to be refracted. Unless an incident beam of light is perpendicular to the surface, refraction changes the light’s direction of travel. For this reason, the beam is said to be “bent” by the refraction" "If n2 is equal to n1, then (i) is equal to (r) and refraction does not bend the light beam, which continues in the undeflected direction" Please notice , here he is saying "When refractive index of both the mediums are equal then REFRACTION DOESN'T BEND THE LIGHT". That means he is calling the situation as refraction. 2. There is a video by Professor HC Verma on his youtube channel where Sir is clearly addressing this misconception related to refraction of light. Dr HC Verma is a champion in his respective field and I believe he has done alot a research himself before coming forward with his video. Here's the link: th-cam.com/video/3S2IRz7AjYg/w-d-xo.html 3. Now let's finally talk about the different online resources and why they define refraction like that. Usually authors define refraction and refraction simultaneously. They say that "If a ray of light strikes the surface of a transparent glass obliquely then a part of light returns back to the same medium (reflection) and a part of light travels into glass (refraction) and its direction of propagation changes". When immature authors look at this definition , they feel that "Oh , see in refraction light has bent and hence refraction means bending of light". That is why most online websites and immature textbooks and even maybe some good ones which didnt pay much attention (because physics in so diverse) , define refraction like you are stating. But now its high time that for the sake of science , the correct terminology should be brought to everyone's notice. 4. Final Conclusion: I am not here to challenge the whole physics world. I am here to learn physics and share some of it because that is how people grow. I first came to know about this from Professor HC Verma and then researched about it. When i finally saw that even Resnik Halliday has clearly said "Refraction is change in medium" and "When a ray of light strikes a transparent surface normally , it passes undeviated. This situation is also refraction , even snell's laws are perfectly valid here". Happy Learning!
Good question! Unfortunately, this question has come to your mind because of a misconception which is widely propagated by various teachers and authors (in class 12). You must first understand the definition of a scalar: "Any quantity which requires only magnitude to completely express their meaning is known as scalar". They dont have any direction in space ( i.e no x ,y and z componets) Since it doesn't require direction hence the direction of scalar quantities are undefined. NOTICE that I have used the term "undefined" , that means that by default there is no direction .However, if we want then for a "specific need we can define their direction". Scalar quantities can be added by using "ordinary algebra". eg: Electric Current doesn't require any direction to express itself. Just the value is sufficient , but still we assign a direction to electric current to convey "the direction of flow of charge in a conductor". What about area? Area is for sure a SCALAR QUANTITY. The total area of a cube can be simply obtained by adding the area's of 6 squares it is made up of (=6a2). However , in electrostatics (class 12) there is a quantity called " Electric Flux". Electric Flux basically denotes the number of electric field lines passing through an AREA Perpendicularly. Now listen very carefully, In this case we define a VECTOR corresponding to the Surface Area , whose value is same as surface area and direction is perpendicular to the surface.This vector is termed as AREA VECTOR. AREA = Surface area of the surface AREA VECTOR = A vector quantity defined by scientist for a specific need ( here to represent direction of electric field lines). This vector has value equal to the surface area and direction is perpendicular to the surface. Why is this vector needed? Number of electric field lines passing through the surface has a direction. For representing this direction , such a vector is defined and they say "Electric Field lines are in the direction of area vector or opposite to the direction of area vector". Conclusion: 1. AREA has only magnitude and no direction and it is a SCALAR Quantity. 2. AREA VECTOR is a quantity specifically defined to represent direction of Electric Field lines passing through a surface". I personally don't like the term "AREA VECTOR" because beginners somehow misinterpret AREA as a VECTOR , so I prefer calling it DIRECTION VECTOR. I hope that clears your doubt. I will make a video on this when i get time to answer it using more examples.
Awesome 👍
Sir if energy is a scalar quantity how can it be negative.
@@Ayushmangarnaik738 Awesome question. Please watch my latest video on meaning on sign convention in physics. Its a 45 min long video and you will not only get answer to your question but also never have any doubt about positive and negative signs in physics.
Sir if pseudo force is imaginary and only experience by observer in non interial frame then why pendulum in a accelerating train appear to move backward by interial observer also
This is an excellent question! Alot of students get this doubt. The answer however is very simple.
Suppose that the person is standing on ground and the train having a pendulum attached to its ceiling is at rest in front of him.
Since the train is at rest , so the pendulum inside is also at rest.
When the train suddenly starts accelerating , the body of the train moves ahead along with the point of suspension of the pendulum but the bob of the pendulum is not able to share the motion of the train immediately.
Thus the body if the train moves ahead along with point of suspension but the bob is left behind and it appears as if the bob moves backward because of some force acting on it.
In reality, the train moves ahead and bob lags behind and that gives us the observation
Sir can you please provide an example where there is bending of light and no change in medium. This example itself will be enough to prove that bending of light is not refraction but an inessential consequence of refraction.
I hope u will see my comment🤞
Edit :- is it even possible that there is bending of light without the change in medium of propagation of light? I mean does light only bend when it travels from 1 medium (rarer) to another medium (denser) obliquely.
Good question!!
See Bending means change in direction of propagation and it happens even during reflection isnt it?
Some people feel bending happens only towards the normal or away from the normal , which is not the case.
Conclusion:
Reflection= returning of light into the same medium
Refraction= Light entering another medium.
Bending may or maynot happen in both the cases.
So the answer to your question "Give an example where light bends without change in medium" will be reflection of light.
I hope that answers your question
@@SouhardyaSutradhar thanks for answering sir
Sir i Googled this topic and the whole internet is filled with that bending of light when light travels from one medium to another obliquely.
Now there are qus out there which ask - give condition when no refraction occur and they give answer that no refraction occurs when light travels perpendicular to the surface. Even school, coaching, har jagah yahi CHL rha even badi badi websites me bhi yahi dikha rahe. I study in aakash institute, vahan ke physics teacher ne bhi yahi kaha ki refraction tab nahin hota hai jab light perpendicular to the surface strike karta hai.
Sir pls help karo🙏🙏🙏. Maine lagta hai jyada elaborate kardiya isliye in short qus yeh hai -
Jis cheez ko aap misconception keh rahe hain wahi har jagah bataya ja rha hai.
It feels like u are challenging the whole physics world.
8:02 sab Kae rahe yeh refraction nahi hai
@@lalitadevi365 I appreciate your enthusiasm for physics and your research. Dont worry , I will answer each one of your questions.
First let me tell you where I am coming from and why have I made this video.
1. It is clearly mentioned in Fundamental of Physics , by Resnik Halliday Walker (which is one of the most authentic sources of physics) where the author says and I quote
"The travel of light through a surface (or interface) that separates two media is
called refraction, and the light is said to be refracted. Unless an incident beam of
light is perpendicular to the surface, refraction changes the light’s direction
of travel. For this reason, the beam is said to be “bent” by the refraction"
"If n2 is equal to n1, then (i) is equal to (r) and refraction does not bend the light
beam, which continues in the undeflected direction"
Please notice , here he is saying "When refractive index of both the mediums are equal then REFRACTION DOESN'T BEND THE LIGHT". That means he is calling the situation as refraction.
2. There is a video by Professor HC Verma on his youtube channel where Sir is clearly addressing this misconception related to refraction of light. Dr HC Verma is a champion in his respective field and I believe he has done alot a research himself before coming forward with his video.
Here's the link: th-cam.com/video/3S2IRz7AjYg/w-d-xo.html
3. Now let's finally talk about the different online resources and why they define refraction like that.
Usually authors define refraction and refraction simultaneously. They say that "If a ray of light strikes the surface of a transparent glass obliquely then a part of light returns back to the same medium (reflection) and a part of light travels into glass (refraction) and its direction of propagation changes".
When immature authors look at this definition , they feel that "Oh , see in refraction light has bent and hence refraction means bending of light". That is why most online websites and immature textbooks and even maybe some good ones which didnt pay much attention (because physics in so diverse) , define refraction like you are stating. But now its high time that for the sake of science , the correct terminology should be brought to everyone's notice.
4. Final Conclusion:
I am not here to challenge the whole physics world. I am here to learn physics and share some of it because that is how people grow. I first came to know about this from Professor HC Verma and then researched about it. When i finally saw that even Resnik Halliday has clearly said "Refraction is change in medium" and "When a ray of light strikes a transparent surface normally , it passes undeviated. This situation is also refraction , even snell's laws are perfectly valid here".
Happy Learning!
Sir area is scalar or vector?plz explain
Good question! Unfortunately, this question has come to your mind because of a misconception which is widely propagated by various teachers and authors (in class 12).
You must first understand the definition of a scalar:
"Any quantity which requires only magnitude to completely express their meaning is known as scalar". They dont have any direction in space ( i.e no x ,y and z componets)
Since it doesn't require direction hence the direction of scalar quantities are undefined.
NOTICE that I have used the term "undefined" , that means that by default there is no direction .However, if we want then for a "specific need we can define their direction".
Scalar quantities can be added by using "ordinary algebra".
eg: Electric Current doesn't require any direction to express itself. Just the value is sufficient , but still we assign a direction to electric current to convey "the direction of flow of charge in a conductor".
What about area?
Area is for sure a SCALAR QUANTITY. The total area of a cube can be simply obtained by adding the area's of 6 squares it is made up of (=6a2).
However , in electrostatics (class 12) there is a quantity called " Electric Flux".
Electric Flux basically denotes the number of electric field lines passing through an AREA Perpendicularly.
Now listen very carefully,
In this case we define a VECTOR corresponding to the Surface Area , whose value is same as surface area and direction is perpendicular to the surface.This vector is termed as AREA VECTOR.
AREA = Surface area of the surface
AREA VECTOR = A vector quantity defined by scientist for a specific need ( here to represent direction of electric field lines). This vector has value equal to the surface area and direction is perpendicular to the surface.
Why is this vector needed?
Number of electric field lines passing through the surface has a direction.
For representing this direction , such a vector is defined and they say "Electric Field lines are in the direction of area vector or opposite to the direction of area vector".
Conclusion:
1. AREA has only magnitude and no direction and it is a SCALAR Quantity.
2. AREA VECTOR is a quantity specifically defined to represent direction of Electric Field lines passing through a surface".
I personally don't like the term "AREA VECTOR" because beginners somehow misinterpret AREA as a VECTOR , so I prefer calling it DIRECTION VECTOR.
I hope that clears your doubt. I will make a video on this when i get time to answer it using more examples.