Light-reflection and refraction/CBSE/Grade-10/Physics

追加: 2026-05-11

[00:00:43]Hello students, welcome to the student brand.

[00:00:47]This is today topic is light reflection and refraction.

[00:00:54]Light reflection and refraction.

[00:00:58]Okay. So let's start the topic.

[00:01:03]Let's start the topic.

[00:01:05]Okay. So in the chapter, so we are going to discuss reflection of light and loss of reflection.

[00:01:29]angle of deviation.

[00:01:37]Okay, let's start the topic.

[00:01:48]Hello everyone, welcome to the student the brand. This is so today we are going to discuss about light reflection and refraction. Light reflection and refraction. Right? So let's see how. So I'm taking light reflection and refraction topic refraction.

[00:02:21]So what is light?

[00:02:23]Light is a form of energy. Uh light is a form of energy which gives the sensation of light. When light incating on it also it reflect back the bouncing back of the light from the reflecting surface is called reflection of light. The bouncing back of the light from the reflecting surface is called a reflection of light.

[00:02:41]Okay. So after in after incidenting the plain surface. Okay. So after reflection only it reaches to the eyes. When light incident on the surface after reflection it reaches to our eyes. Then only we can able to see the objects. Yes or no? So without that we can't able to see. Once you close your eyes will you able to see anything? No. So once you show close your eyes you can't able to see anything. Once you open your eyes then you can able to see beautiful things in front of us. So how it is happening?

[00:03:18]Because when light incident on it so after reflection reaches to our eyes then we can able to see the object.

[00:03:26]Okay. So due to reflection of light. So what is the reflection of light?

[00:03:30]Reflection of light. So I'm taking the plane mirror. This is a plane mirror.

[00:03:36]This a plane mirror. So incident ray.

[00:03:41]Incident ray and reflected ray.

[00:03:44]And the light ray which is perpendicular to the plane surface is called normal line. Incident ray reflected ray normal line. The angle between incident and normal end is called angle of incidence.

[00:03:56]Angle between reflected and normal is called angle of reflection.

[00:04:01]And uh here you can observe this is the undeated line. Unated line actually light moves in a straight line path. In a homogeneous medium light moves in a straight line path. Right? So this the antiator light. This is the antiator line. So it is not deviating the surface deviating the path. It's not deviating. Okay. So if it is deviating means it bends towards the normal line.

[00:04:32]It moves towards the normal line like that. So if it is not deviating it moves in a straight line path, right? So angle between incident and normal line is called angle of incidence. Angle between reflected and normal is called angle of reflection. Angle between reflected and undated L is called angle of deviation.

[00:04:50]Okay. The bouncing back of the light from the reflecting surface is called reflection of light. The bouncing back of the light from the reflecting surface is called reflection of light. So I hope it is very clear. Right now uh coming to loss of reflection loss of reflection.

[00:05:11]Loss of reflection. So point number one incident reflected ray normal line lies on the same place. Incident reflected normal line lies on the same plane. And coming to the point number two, angle of incidence is equal to angle of reflected. Angle of incidence is equal to angle of reflection. I hope it is very clear. So loss of reflection incident reflected normal lies on the same plane. Angle of incidence is equal to angle of reflection. So this about loss of reflection. Loss of reflection.

[00:05:48]So now we'll discuss about uh angle of deviation. Angle of deviation. So linear angle and one more point is here you need to understand uh glancing angle of incidence, glancing angle of reflection. Sir, what do you mean by glancing angle of incidence and glancing angle of reflection? So the angle between incident ray and plane surface is called a glancing angle of incidence. Angle between reflector and plane surface is called glancing angle of reflection.

[00:06:25]Okay. So the angle between incident and plane surface glancing angle of incidence angle between reflector and plane surface glancing angle of reflection.

[00:06:36]Okay. So now now you can observe uh here angle of incidence plus angle of reflection plus angle of deviation angle of incidence plus angle of reflection plus angle of deviation equal to 180°.

[00:06:53]Right? From loss of reflection we can write angle of incidence is equal to angle of reflection. From loss of reflection angle of incidence is equal to angle of reflection. So I can write angle of incidence plus angle of incidence plus angle of deviation = 180° angle of deviation = 180 minus 2 angle of incidence angle of deviation = 180us 2 angle of reflection understood or not I hope it is very clear angle of deviation equal to 180US to angle of incidence angle of deviation equal to 180 is to angle of reflection.

[00:07:37]So these two points are very very important. Right? The bouncing back of the light from the reflecting surface is called reflection of light. Incident ray reflected ray normal line. Angle between incident ray and normal line is called angle of incidence. Angle between reflected and normal line is called angle of reflection. And angle between reflected ray and plane surface is called glancing angle of incidence. And angle between reflected and plain surface is called glancing angle of reflection. So these points are very important. Coming to loss of reflection, incident reflected normal lies on the same plane. Angle of incidence is equal to angle of reflection. And here you can observe angle of incidence plus angle of reflection plus angle of deviation equal to 180°. Angle of incidence plus angle of incidence plus angle of deviation equal to 180°. So angle of deviation equal to 180 - 2 angle of incidence angle of deviation equal to 180 - 2 angle of reflection. I hope uh these points are very clear right. So uh let's discuss about uh regular reflection and irregular reflection. Regular reflection and irregular reflection.

[00:09:07]So let's discuss about regular reflection and irregular reflection.

[00:09:12]Regular reflection takes place on smooth surface.

[00:09:17]Regular reflection takes place on smooth surface. Okay. So here you can observe this a plain surface.

[00:09:28]This is the plain surface.

[00:09:31]Okay. So plain surface understood or now this is the plain surface.

[00:09:40]So incident beam is par. These are incident light rays.

[00:09:45]These incident light rays are par to each other.

[00:09:50]Okay.

[00:09:54]These incident light rays are par to each other.

[00:09:58]So incident par beam. So I can say incident incident parallel beam and here you can observe reflected parall beam.

[00:10:15]Okay. After incidenting after We will get reflected beam also. Par beam. Okay. Reflected par beam.

[00:10:38]Reflected.

[00:10:40]Parall beam.

[00:10:45]Are you understanding or not? So observe carefully. Incident beam is parallel then reflected beam also parallel to each other. So there are three types parallel, convergent, divergent.

[00:10:58]So here light will consider as a ray.

[00:11:02]Light we are taking as a ray. Light is a ray. Okay. So in the ray optics so we are talking light reflection refraction.

[00:11:11]Right? So in this topic we'll consider light as a ray and a single ray. If you take there's ray of light single light. Okay. Here number of lighters together. Number of light rays together we can consider beam. Okay. Number of light together we'll consider as a beam. Here par beam is incident on it. Then reflected beam also parall to each other. So this type of reflection is called regular reflection. This type of reflection is called regular reflection. Right? Yes.

[00:11:47]So regular reflection takes place on plane mirror. Regular reflection takes place on plane mirror. Coming to irregular reflection.

[00:11:58]This is the irregular surface.

[00:12:03]Irregular surface. So incident light rays are parall to each other.

[00:12:09]Incident light rays are par to each other. But reflector light rays are not par to each other. Sir why?

[00:12:16]Because surface is not smooth right surface is not smooth. It is irregular surface. So incident light rays are par to each other. After reflection light rays moves in different direction.

[00:12:30]Light rays moves in different direction.

[00:12:32]These light rays are moving in this direction. These light rays are moving this direction. These light rays are moving in different directions. Okay. So these are incident light rays.

[00:12:43]Incident light rays and coming to your reflector light rays.

[00:12:51]Reflector light rays.

[00:12:56]So observe carefully here. So this is the regular reflection.

[00:13:02]Regular reflection.

[00:13:06]Regular reflection. Incident light rays are par. Then reflector light rays are also parallel to each other. So that's why it is called regular reflection.

[00:13:13]Regular reflection takes place on smooth surface. So surface is very smooth.

[00:13:19]Okay. So coming to irregular reflection.

[00:13:22]Incident light rays are parall but reflective light rays are not parall to each other.

[00:13:27]Surface is irregular. So this is also called irregular reflection or diffuser reflection. Irregular reflection or diffuser reflection. Okay. Irregular.

[00:13:40]Irregular or diffuser deflection irregular or diffusive reflection. So irregular reflection takes place on rough surface.

[00:13:58]This regular reflection takes place on smooth surface.

[00:14:02]Example plane mirror here. Uh smooth surface.

[00:14:08]Okay. Smooth surface. Example plane mirror I'm taking here whereas irregular reflection takes place on rough surface the surface is rough surface rough surface example wall example wall we can take understood or not so this is about regular reflection and irregular reflection regular reflection and irregular reflection so smooth surface Surface Incident light. Incident beam is parallel. Reflected beam also par.

[00:14:44]Regular reflection. Example plane mirror to rough surface. Incident light rays are par but reflected light are not parall to each other. Irregular reflection is also known as diffuser reflection. Example wall, book, table, anything we can say. And coming to the next one, object and image.

[00:15:15]Object and image.

[00:15:29]So object and image. So object is nothing but so normally you can take two light tube light bulb sun glow from this object light rays are coming right. So minimum light rays are required to form the image of the object is two. When these light rays are meeting at one point reflect the light ray. So when light rays incident on mirror. So after reflection if two light rays will meet directly that is called real image. If you're extending the reflector light rays, extended reflector light rays are meeting at one point there virtual image will form and coming to the object if directly incident light are coming from the point that is called what is that real object after reflection. So like we can say light rays are coming from the source after inc after reflection reflector light will meet. If we are extending the incident light extended incident light are meeting at one point their their object is there that is virtual object. Now I'll draw the diagram. So with the help of diagram I will explain. Let's start here. You can observe this the plane mirror.

[00:16:43]So this the plane mirror.

[00:16:50]So I'm taking the plane mirror this one.

[00:16:54]Okay. So light rays are coming from the source like this. After reflection the light rays are meeting at one point.

[00:17:06]Here you can observe this I1 R1 I2 R2. This the real image.

[00:17:16]Real image.

[00:17:21]Okay. real element and here you can observe we are extending the incident rays.

[00:17:31]So here you can observe I1 I2 this is R1 R2 R1 R2 are meeting at one point there's a real image directly reflect light rays are meeting at one point directly reflect light rays are meeting at one point there is a real image we are extending the incident light rays extended incident light rays are meeting at one point their image is that is not image that is object that is a virtual object virtual object And here you can observe.

[00:18:08]So this is the real object from here light rays are coming.

[00:18:15]Okay.

[00:18:17]So after reflection here you can observe.

[00:18:23]So if you observe here directly reflect the light rays are meeting.

[00:18:28]directly reflect the light trace are meeting that's why this is a real image understood or not real image here this is a real object right real object real object and we are extending so I1 I2 R1 R2 so we are extending reflector light tracer extended reflector light rays are meeting at one point. Extended reflector light rays are meeting at one point.

[00:19:03]Right? These are extended reflector light rays. So that's why it is called virtual image.

[00:19:09]In these two diagrams you need to observe one thing. If light rays are meeting directly either incident light are meeting that is real object either reflector light rays are meeting directly that is called real image. But whereas extended incident light extended reflector light rays extension if the light rays are extended and meeting that is virtual. Okay. If incident light are extended that is virtual object. If reflector light are extending that is a virtual image. Okay. So I hope it is very clear. This is a virtual image and virtual object.

[00:19:45]Now, so by observing these two diagrams, we can conclude that object and image.

[00:19:54]What about object here? Object is virtual, right? What about image? Image is real. So, are you understanding or not? Observe carefully. If you observe the diagram, then so it will be very clear. So, no need to worry about it.

[00:20:08]So, you must observe the diagram. That's enough. Observe the diagram here. So here these are I R1 R2 directly reflector light rays are meeting right these are reflector light rays. So we are extending the incident light extended incident light are meeting at one point their virtual object. If you are extending a incident light rays there virtual object is there directly light rays will meet there is a real limit here you can observe this the point from here light rays are coming like you see the bulb and you can see the torch light and you can see the tube light and you can see the sun from that source okay the source which is giving the light the object which is giving the light that is source The object which is giving the light that is called source.

[00:21:00]Okay. Here like if you see uh in our home okay two light or electrical bulb a torch also we can see from that point light rays are coming right. If the light rays are coming from that point that is real object because the light rays are coming from directly from that point that's why it is a real and here you can observe after reflection we are extending the reflect light rays R1 R2 R1 R2 or extended reflect light so here I'm here I did I drew with the dotted lines so remaining cases except this case so reming In all the cases I do I drew the normal lines but only in this case I drew know dotted lines. So what the dotted lines represent? What do lines giving us? Okay. So what hint dotted lines dotted lines are giving?

[00:22:02]So the dotted lines are representing virtual im virtual either it is incident extended incident light that is a virtual object extended reflect light there is a virtual image. So keep in mind very very important if dotted lines are there if lines are extended extended dotted lines are meeting at one point that is virtual image directly light will meet that is a real if it is incident light real object if it is reflect light real image extended incident light virtual object extended reflector light virtual image right yes so the conclusion is if object is virtual, image is real, object is real, what about image? Image is virtual.

[00:22:54]Okay? So you need to understand, you need to observe, you need to practice, you have to carefully observe these two diagrams. Okay?

[00:23:06]A clean observation is required because here by observing these two diagrams we can conclude that we can conclude that if the object is real image is virtual. If the object is virtual image is real vice versa.

[00:23:24]Okay. So if one thing has happened so automatically reverse also will happens.

[00:23:30]Okay. Reverse also will takes place. So that you have to keep in mind. Okay. In the plane mirror object is real image is virtual. If object is virtual image is real right. So sir why you are stretching this point this much time because in the coming uh concepts these points are very very important like a lateral inversion and uh nature of the m formed by the plane mirror there three marks question will come. So in that also these points are very very important. That's why I'm again and again and repeating.

[00:24:05]Okay. So make sure that you listening, understanding and practicing. Right.

[00:24:11]Yes. Now let's start one more.

[00:24:24]Shall we discuss about nature of the mirror formed by the plane mirror?

[00:24:29]Nature of the image formed by the plane mirror. So now you can see this is a plane mirror.

[00:24:37]This is a plane mirror.

[00:24:41]So this is the object as I mentioned.

[00:24:47]How many light rays are required to form the image of the object?

[00:24:51]How many light rays are required to form the image of the object? Minimum two light rays are required to form the image of the object. Right? Minimum light rays are required to form the image of the object is two.

[00:25:02]Okay? So when light ray is incidenting along the normal line suppose if the light ray is passing along the normal line it moves in the same direction.

[00:25:15]So are you understanding or not? When light ray is passing along the normal line, it rebounces or it moves or it reflect in the same direction or it retains its original path.

[00:25:29]Okay. So that is one point to have to keep in mind. And the second point is second point is so here this height of the object here you can observe AB height of the object one light I'm taking like this after reflection passes another light I'm taking like this it will be reflected back and here also you can See so actually we need to draw the dotted lines right sir why you are drawing dotted lines why we have to draw the dotted lines virtual image is forming that's why virtual image is forming okay a dash and b dash a dash and b dash Is it clear?

[00:26:39]AB A - dash B dash.

[00:26:43]Okay. So in the previous case, in the previous concept I mentioned this point. What is that point?

[00:26:54]If the object is real image is virtual in the previous concept just now I explained right. So in that concept I mentioned so I mentioned that if the object is real image is virtual if the object is virtual image is real right. Yes. So object is real image is virtual.

[00:27:17]And here what is this one? object.

[00:27:23]This the object and what about this one image so this the height of the object and this one is the height of the image.

[00:27:36]Okay. So I'm representing all the points clearly one by one to understand. So this height of the object height of the object and this one will be considered height of the image and the distance between object to mirror is called object distance. The distance between mirror to image is called image distance. Here you can observe the distance between object to mirror. This is the mirror. The middle one is the mirror. Right? So I'm taking this mirror mirror. So the distance between object and mirror. So this distance is called object distance. And this distance is called image distance. So object distance is equal to image distance. And coming to the second one, height of the object is equal to height of the image.

[00:28:25]And coming to the third one, magnification is + one because virtual erect and same size of the image will form in the plane mirror.

[00:28:35]Virtual erect and same size. virtual erect and same size of the image will form in the plane mirror. That's why magnification is plus one. And coming to the fourth one, it also shows lateral inversion.

[00:28:51]Sir, what do you mean by lateral inversion? What do you meaning of lateral inversion? Lateral inversion.

[00:29:00]Lateral inversion.

[00:29:05]Lateral inversion is nothing but So stand in front of the mirror.

[00:29:11]Okay? Go and stand in front of the mirror and uh lift your right hand.

[00:29:17]So it appears in the left side of the image.

[00:29:20]So go and stand in front of the mirror and lift your right hand. Right hand.

[00:29:27]Okay. Our right hand it appears in the left side of the image in the mirror. So if you lift your left hand it appears in the right side of the image in the mirror understood or not. So the phenomenon of converting of right side of the object appears to be left side of the image. Left side of the object appears to be right side of the image or simply we can say the mirror image.

[00:29:56]Okay. So that is called lateral immersion.

[00:30:01]later inversion. So I will give one question. So will you able to answer?

[00:30:08]Uh capital letters you have to take.

[00:30:10]Okay. Take capital letters uh right from starting A to Jed. Which letter does not show lateral inversion?

[00:30:21]So do comment in the comment section which letter does not show lateral inversion.

[00:30:28]So let me know.

[00:30:31]Okay. So if you like the concept, if you like the explanation, if you like the channel, do like, share and subscribe to student the brand. And I'm I'm I'm giving the course for CBSC grade and physics. Okay. So with a very uh less cost, okay, you can contact the number.

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[00:31:05]So now you can see object distance is equal to image distance. Height of the object is equal to height of the image.

[00:31:11]Magnification is + one. And also it shows lateral inversion. Lateral inversion is nothing but the phenomena of converting of right side of the object appears to be left side of the image. Left side of the object appears to be right side of the image. Okay. So just if you stand in front of the mirror, our right hand uh object appears to be left side of the image. Left side of the object appears to be right side of the image. This mirror image is called lateral inversion. Right? I hope it is very clear. Next So now plane mirror completed.

[00:32:09]So now we'll discuss about uh spherical mirror.

[00:32:16]Okay. Let's discuss about spherical mirror spherical mirrors. Okay. In plain mirror you can observe a light incident after reflection. So till now we discussed about it. Coming to spherical mirrors.

[00:32:45]Here uh mirrors are flat okay position but in uh spherical mirrors mirrors are in curvver shape mirrors are in curve shape so we'll discuss that point okay so let's start so very very important greater physics to those are going to those are upcoming 10th class okay for them exclusively I'm launching the course CBSC grade and physics okay four chapters will be discussed in detail uh questions also will be discussed so doubt clarification will be there so let me know so if you need the classes if you need the classes Okay. So already given the number in the channel banner. One check the channel banner and you can contact to me.

[00:33:54]Now spherical mirrors.

[00:33:59]So here if you take the mirror which is in the form of curve curve shape.

[00:34:06]The mirror which is in the form of curved shape that is called spherical mirror.

[00:34:12]Okay. So here I'm taking the concave mirror.

[00:34:16]This is a concave mirror.

[00:34:18]Concave mirror. Sir, how can you say whether it is concave or convex?

[00:34:24]Reflection takes place inward that is called concave mirror. Reflection takes place outward that is called convex mirror. Reflection takes place inward that is called concave mirror.

[00:34:35]Reflection takes place outward that is called convex mirror. Here you can observe when light ray. So I'm taking here.

[00:34:44]Now you can observe.

[00:34:51]So this is a concave mirror concave.

[00:35:09]Understood? So it is a part of this sphere. Reflection takes place inward.

[00:35:16]So that's why it is called concave mirror. Whereas reflection takes place outward.

[00:35:22]Reflection takes place outward. That is called convex mirror. This one is concave mirror.

[00:35:30]Concave mirror. And coming to this one is convex mirror.

[00:35:37]Convex mirror and concave mirror.

[00:35:40]Okay. So here concave mirror is also known as converging mirror. Sir why you are calling concave mirror is a converging mirror because whenever light rays are incident on it whenever light rays are incident on it after reflection those light rays are moving towards the principal axis after reflection light rays will move towards the principal axis. Whereas convex mirror after reflection light rays will move away from the principis.

[00:36:08]Light rays will move away from the principle axis. So concave mirror is also known as converging mirror whereas convex mirror is also known as diverging mirror.

[00:36:18]Okay. So now So now we'll discuss about terms related to spherical mirror. So till now we discussed about related to plane mirrors. We discussed like a reflection, loss of reflection, angle of deviation and regular reflection, irregular reflection and the nature of the image formed by the plane mirror. After that uh spherical mirrors, concave mirror, convex mirror. The mirror which is in the form of curve shape is called con spherical mirror. The mirror whose reflection takes place inward is called concave mirror. The mirror whose reflection takes place outward is called convex mirror. Right? So now we will discuss about terms related to spherical mirror. We'll discuss about terms. Okay.

[00:37:19]What are the terms? We'll see. Here I'm taking this a concave mirror. What is this one? Concave mirror. Understood or not? Yes. Actually it is a part of the sphere. Right? It is a part of the sphere. The mirror which is the part of sphere. So the center of the imaginary sphere in which mirror is a part. The center of the imaginary sphere in which mirror is a part. At the midpoint of the mirror is called pull. Midpoint of the mirror is called four. The center of the imaginary sphere in which mirror is a part. Midpoint of the mirror is called four. And the line joining of center of curvature and pole is called principal axis. Central curvature pole. And third one is principal axis.

[00:38:09]Principal axis.

[00:38:11]And coming to the fourth one, the distance between central curvature to pole is called radius of curvature.

[00:38:19]Radius of curvature. And coming to the fifth one.

[00:38:23]So after reflection, after reflection, light rays are meeting at one point. Right here you can observe these light rays are coming from infinity.

[00:38:36]So if you observe here these light rays one two these light rays are coming from infinity after reflection those light rays are meeting at one point that is called focus this is called focus focus and the sixth one the distance between focus to pole is called focal length focal length and coming to the seventh one width of the reflecting surface where reflection of light takes place.

[00:39:07]So m n. So this see m and n is the aparture.

[00:39:15]Aparture understood or not. Center of the imaginary sphere in which mirror is a part. Midpoint of the mirror is called pole. Line joining of center curvature and pole is called principal axis. The distance between central curvature to pole is called radius of curvature.

[00:39:31]And after reflection all light rays are meeting at one point on the principal axis that is called focus. Actually it is called a principal focus. Capital F is called a principal focus. Simply we can say focus.

[00:39:47]Okay. So uh small F here don't get confused between capital F and small F.

[00:39:54]Here capital F is denote focus. Small F denotes focal length.

[00:40:01]This is called distance. That is a point.

[00:40:04]F is a point. Small F is a focal length and aperture. Width of the reflecting surface is called aperture. Width of the reflecting surface is called aperture.

[00:40:17]Understood or not? So these are related to terms related to spherical mirror.

[00:40:22]These are terms related to spherical mirror or nomicature.

[00:40:27]nomicature terms related to spherical mirror. Next, so we'll discuss about rare rules.

[00:40:37]Rare rules. So you are going to exam hall, right? For writing exam. What you need? You need weapons, right? Pen.

[00:40:48]Weapons in the sense pen, pencil, exam pad, hall ticket.

[00:40:55]Okay. Uh all these things we need understood or not for writing exam we need. So pen, pencil, eraser, sharpener.

[00:41:08]Okay, exam pad. Okay, all these things are required to write exam.

[00:41:15]Okay, write an exam. So for drawing the image formation of conc convex mirror or image formation of image formation by a concave mirror image formation by a convex mirror whatever it may be whatever it is you need rare rules yes or no you need ray rules so those rare rules we'll discuss so we have to follow the rules yes or We have to follow the rules. So you're going on a road. So we have to follow traffic rules.

[00:41:55]Okay. So you are going to college, you have to obey the uh management rules.

[00:42:01]Yes. So no not like that. I have to go I I I will go in my own way. So I will take my own rules. So not possible that.

[00:42:12]Yes. Okay. So now here you can see so what we are discussing ray rules right so shall we discuss about concave or convex concave or convex concave I'll discuss concave so concave mirror is also known as converging mirror how many rules are there are four rules till now we discussed about Till just now we discussed about pole focus, center curvature. Just now we discussed about pole focus and center curvature. So this the pole focus center curvature. So one light ray is coming from infinity after reflection passes through focus.

[00:43:02]Second one light ray is passing through focus. This is the pole focus and central curvature light ray is passing through focus.

[00:43:15]After reflection after reflection it moves towards infinity light here in the first case you can observe the second one is exact opposite of first one.

[00:43:31]The second case is exactly opposite to the first one.

[00:43:36]Why? Here you can see light ray is coming from infinity after reflection passes through focus. Right? Here also same thing the light ray is passing through focus after reflection moves towards infinity. And coming to the third one coming to the third one here you can observe here this is a pole focus center curvature.

[00:44:04]Light ray is passing through central curvature.

[00:44:10]Light ray is passing through central curvature. It moves in the same direction. Light ray is passing through center curvature. It moves in the same direction.

[00:44:20]Okay. So this the pole focus center curvature. Pole focus and center curvature. Take the light ray incident at the pole it reflect back. So you know the reflection of right. So the starting of the chapter we discussed starting of this particular chapter we discussed when light incident on it reflect back the bouncing back of the light from the reflecting surface is called reflection of light. Okay.

[00:44:51]Incident reflected normal line angle of incident angle of reflection angle of deviation and glancing angle of incidence glancing angle of reflection.

[00:44:58]All those points we discussed right in the starting of the class starting of this chapter right. So likewise if the light I incident at the pole it reflect back. So as like when light incidenting on the plane surface it reflect back you know right the light incident on the plane surface it reflect back. So angle between incident and normal is called angle of incident. Angle between reflected and normal end is called angle of reflection.

[00:45:25]Okay. So I hope it is very clear understood or not. So this is about concave mirror. Sir, what about convex mirror? So do we have four rules for convex mirror also? Yes, for convex mirror also we have four rules. Yeah, same thing. Okay, same same but a different.

[00:45:51]So here you can observe. So this the pole focus center curvature light ray is coming from infinity after reflection it passes through focus passing through focus right and coming to the second one coming to the second one pole focus center curvature so light ray is passing through focus so after reflection moves towards infinity Light ray is passing through focus after reflection most integrated. And coming to the third one this pole focus center curvature light ray is passing through center curvature. Here you can observe it moves in the same direction.

[00:46:44]It moves in it actually it retails at reflect the same path. It retails its original path. It reflect back into the same path. We can take any anyone.

[00:46:59]Okay. And coming to the next one. So what is this mirror? Convex mirror or not? So pole focus center curvature light ray incidenting at the pole it reflect back.

[00:47:13]Okay. So observe carefully. These are rules of concave mirror and convex mirror.

[00:47:20]Concave mirror and convex mirror. Is it clear or not? Do you have any doubts?

[00:47:28]Is it clear?

[00:47:31]Yes.

[00:47:34]Right.

[00:47:36]Okay. Done. So shall we discuss about convex mirror?

[00:47:51]Corvex image formations. We have to discuss Convex mirror image formations.

[00:48:17]Okay, there are six image formations for convex mirror. So first one is so I'm taking this convex mirror.

[00:48:29]So concave what is this one concave concave for concave only six image formations.

[00:48:42]So pole focus center curvature to where you are taking object object is placed at infinity.

[00:48:54]First case is object is placed at infinity.

[00:48:59]So how many light rays are required?

[00:49:01]Minimum two light rays are minimum two light are required to form the image of the object.

[00:49:08]So that's why I'm taking is the focus.

[00:49:12]One letter I'm taking like this one 2 3 object is at infinity. Image is forming at focus. Major of the image is real and inverted. Size of the image is highly diminished.

[00:49:26]Object is at infinity. Image is formed at focus. Nature of the image is real and inverted. Size of the image is highly diminished. And coming to the second one, this is a pole focus center. Object is placed beyond C.

[00:49:51]object is placed beyond C. So one lighter I'm taking like this after reflection passes through focus another light ray is passing through central curvature the image will form between C and F.

[00:50:09]Object is placed beyond C.

[00:50:13]Image is forming between C and F. What is the nature of the image? real and inverted size of the image is diminished.

[00:50:27]Size of the image is diminished compared to the object image size is decreased.

[00:50:32]And coming to the third one.

[00:50:57]So pole focus center curvature.

[00:51:04]So object is placed at C.

[00:51:08]Image also will form at C.

[00:51:13]Object is placed at C. image also will format. See one light I'm taking like this.

[00:51:29]Objective C image is formed at C. Nature of the image is real and inverted. Size of the image is same size.

[00:51:39]Object is placed at C. Image also will form at C. Nature of the image is real and inverted. Size of the image is same size. That is the third one. And coming to the fourth one.

[00:52:04]So here you can observe this the pole focus center curvation. So previously I placed at C. Now I'm placing it uh placing between C and F right. So now you can observe one light I'm taking like this it passes through focus another lighter is incidenting at the pole it reflect back so the image will form here.

[00:52:33]Okay. So object is placed between C and F image will form beyond C.

[00:52:41]Nature of the image is real and inverted. Size of the image is enlarged.

[00:52:47]Okay. Compared to the object, image size is increased. Compared to the object, image size is increased. So this is the fourth one. And coming to the fifth one.

[00:53:04]Fifth one.

[00:53:11]So pole focus central curvature light ray is object object is placed at f one light I'm taking like this another light incidenting at the pole it reflect back okay these light rays will meet at infinity because this light these lines are par to each other right so this will become parall to each other that's why those light rays will meet At infinity object is placed at f image will form at infinity. Nature of the image real and inverted and size of the image is highly enlarged because it is formed at infinity. So absolutely the image is highly enlarged. Right? Okay done. So next one the six is very very important.

[00:53:58]So expected for three marks. So very very important question. So expected for three marks. I'm drawing the diagram. So observe carefully. So sixth one this the concave mirror very very important. So observe carefully this the pole focus central curvature object is placed between F and P one light I'm taking like this so another light ray here you can observe if you are extending this light ray those light rays will meet here okay object is placed between F and P image will form behind the mirror behind the mirror. So what is the nature of the image? Nature of the image is virtual erect and enlarged behind the mirror virtual. Here you can observe object is placed between F and P. So image is formed behind the mirror.

[00:55:02]Nature of the image is virtual erect and size of the image is enlarged. So very very important three marks question expected for board exam. So practice once CBSC great and physics. So I hope it is very clear for a convex mirror only two cases are there. One is at infinity and another one is between infinity and pole. Only two cases that virtual erect and diminished images only will form. Okay. And sign conventions uh all measurements will be taken from the pole in the direction of incident are positive opposite incident is negative. Above the prince is positive.

[00:55:39]Below the prince is negative. Oh, these are sign conventions. Mirror formula 1x f= 1x v plus 1x u. Magnification height of the image by height of the object that is nothing but minus v by u. Okay.

[00:55:51]So these are the points. So if you like the content, if you like the channel, do like, share and subscribe to student brand. Thank you so much. So I'll I'll join to the next class with uh next topic. Thank you so much.