Reflection of Light

Reflection of Light

Hello in this session we are going to discuss a reflection of light. So we'll understand what is the idea of reflection. But before we go to the reflection of light let's understand the categories in which we put different materials based on how They interact with the light which is falling on the surface [I] [to] understand this let's say that you and your friend are standing So let's say this is you and there's a screen in between and there's your friend right so now depending on the kind of screen.

 This is three things could happen the first thing is that you can clearly see your friend Right you can clearly see your friend That is even though there is a screen in between you can clearly see Your friend standing on the other side [as] you can probably imagine that if you put a very clear glass if you use a very clear glass as screen This is what will happen you will be able to see the other person through the glass right, so when such a thing happens We say that the [material] is Transparent So the material is called Transparent and the reason you are able to clearly see on the other side is because Transparent materials allow light.

 they allow Light to pass through them Right so transparent materials allow light to pass through them right So this is the first possibility that you are standing on the other side of the screen and yet you are able to see your friend very clearly and Therefore you could say that The material that is there in between the two of you or the material that has been used to create that screen is Transparent right so the second possibility is that you do not see your friend at all You do not see your friend You do not see your friend or the other person right so if this happens then The reason this would happen would [be] because the screen that is put in between is not letting light pass [through]

 it right because if the power light cannot pass [through] it you will not be able to see your friend and in such a case the [material] will be called an Opaque material so if if some material does not allow light to pass through it That material is called or a said to be an opaque material, right? So opaque materials do not allow light do not allow Light to pass through Right so based on whether or not a material allows the light to pass through it it can be classified as a Transparent Material or a [transom] or an opaque material a third Category a third category could be Where if you imagine that if the screen is made out of paper? You may not be able to see a friend But you might be able to figure out the movement that they are making on the other side of screen Right Imagine looking at someone through a very thin sheet of paper You will not be able to see their face [you] will not be able to recognize them But if there is any movement on the other side of paper.

 You may be able to see it on the screen as to how that person on the other side [of] screen so such a case happens when the material in between is partially aligned some light to pass through right and in such a case the material would be called as Translucent, so it will be called translucent material and The translucent materials allow or rather partially allow partially allow light to pass through Right, so this is what translucent material is they partially allow light to pass [through] them Right, so these are the three categories in words you can Categorize all available materials.

 They are either transparent and allow light to completely pass through them or they are opaque and do not allow any light to pass through them or They are translucent, and they partially allows some light to pass through now I Want you to think about? What I'm about to ask you Which of these three materials do you assume will form shadows? think about that if a given the option that there are Three let's say we have three objects a b and c a is made out of an opaque Material that is light is not allowed to pass through B is made out of a Translucent material and C is mirror of Transparent material so which of the three will form a shadow You may have figured it out that it will be the object a which is made out of opaque material which will Certainly form a shadow because it will stop light from passing through to the other side, right?

So it is the opaque objects which do not allow light to pass through them and hence they form Shadows right even the Translucent Object Will form a Partial Shadow right [you'll] [be] able to distinguish That there is a change in the level of brightness in certain area right the shadow area of this translucent object will have less brightness as compared to the surrounding area, right but if the material is completely transparent [if] the light completely Passes through that thing then you will not see any shadows because shadows are only formed when light is obstructed right So that [is] the idea of how shadows are formed especially through opaque object so now let's Talk about an opaque object So let's say I take a sheet of a material which [is] opaque right now imagine a ray of light falling onto this material Now what do you assume is going to happen to this ray of light? We certainly know [that] it is not going to pass through right because this material is Opaque so what is you is going to have? Well, there are two possibilities One is that this light gets absorbed? Right this ray of light which is falling on this material gets absorbed So this is a possibility which we're not going to discuss in detail [the] other possibility is that this ray of light? bounces back in the Direction from [where] it came right so it could come and fall in this material and then bounce back so this? Bouncing back of light, this is called as a reflection, right?

so this is what is known as a reflection and This Ray which has been reflected back, we'll call it reflected Ray okay, so this one is [your] incident Ray and What has bounced back is called a reflected Ray, right? so Such an instance when light falls on an object and bounces back. This is called as a reflection of light right And a reflection of light is an important phenomena because it is through [deflection] that we are able to see objects So when something reflects light when anything reflects light and that eye that light reaches your eye that is when you are able to sense the Objects right for example you see the wall because the light that falls on the wall Reflects off the wall, and then when it enters your eye you are able to tell that there is a wall that right?

 so what we've understood as Reflection is basically when a ray of light [falls] and bounces back that phenomena is called a reflection, right? So now this reflection can be of two forms one is that the surface is very smooth and Every way of light is reflected [back] very perfectly right, so this would be a regular reflection And you can call it a regular reflection and This is what you would see in case of a mirror So to form a mirror you must smooth out the surface remove all irregular Irregularities and once you create such a perfect [surface] you will get a mirror so I'll explain this in a minute how you're getting a mirror here now imagine an irregular surface something like this so when light falls on this surface, you can see That it will be reflected Not in the same direction.

 They could all go reflected The three ray of light the three incident ray the three parallel rays that we had Reflected in a very symmetric fashion right and here if you draw three parallel rays They are not getting reflected in the same manner [right] so it the reflection is very irregular So this is a regular reflection and this is what you get in case of Let's say a wall so What we understand here is that due to reflection? You are able to see the wall But [you're] not able to see yourself right this is because the reflection is not Very regular and hence the light which is falling on you Is not able to create is not able to reflect perfectly of that wall to be able For you to be able to you see yourself but in case of a glass, what happens is That when light falls on you And then is reflected onto the mirror the light that is falling on you and falling on the mirror is Reflected so perfectly back that you are actually able to see your set right?

And that is why whenever you have a very smooth surface [that] smooth surface could be of metal Marble or any other stone if that surface is very smooth you will be able to see yourself And that happens because the reflection on such surfaces is very regularly right and Please understand that is because of reflection that we are able to see things so we are able to see things We are able [to] see things when light when light is reflected reflected off of them Right,

so when light is reflected off of them Or it reflects of them that is when we are able to see objects, so if there was some material Which would completely absorb the light which is falling on it. You will not be able to see that thing, right? right, so Let's summarize the session what we understood here is the phenomena of reflection of light? We understood that if light falls on a surface and then bounces back then we call it a reflection Right and if there is perfect [if] there is very regular reflection, you will be able to see yourself in that surface But if there is an irregular reflection you will be able to see the surface but not yourself in that surface right And before [all] this we understood how we categorize materials in the three categories Opaque being the material which will not allow light to pass through then we have Translucent materials, which will partially allow the light to [pass] through them And then we have transparent materials where the light can easily pass through those material All right, so that is it [for] this session in the next session. We'll understand how an image is formed.

 Thank you