hi friends do you know that mirrors are of different types plane mirror and curved or spherical mirrors spherical mirrors can be further divided into concave mirror and convex mirror so there are three types of mirrors plane concave and convex in fact I have all these three mirrors on this wall here for you I'm going to go and stand in front of each of these mirrors and let's see what do we observe if I stand in front of the first mirror I appear to be the same height if I stand in front of the second mirror oops I appear to be inverted now if I move close to the mirror I appear to be magnified now if I stand in front of the third mirror I appear to be shorter can you guess the type of mirror for each of these that's right the first mirror is a plane mirror the second mirror is a concave mirror and the third mirror is a convex mirror let's talk about the three mirrors a plane mirror has a plane or flat surface and I'm sure you must have noticed that when you stand in front of a plane mirror you appear to be the same height now let's look at concave and convex mirrors these mirrors are curved mirrors and a very simple way to understand them is using a spoon so I'd like you to pause the video right here and go and get a spoon and it will be great if you can get a larger shiny spoon so are you ready with your spoon a concave mirror is curved inwards so if you look at this side of the spoon can you see it is curved inwards just like a concave mirror now hold the spoon like this and look at yourself in the spoon what do you observe you appear to be inverted and smaller in size or diminished now if you bring the spoon really close to yourself you can see that you are looking magnified but an easier way to do this is to hold an object like a pencil and get it really close to the mirror now you can clearly see the magnification so a concave mirror is the only mirror that can produce an inverted image in this position or a magnified image a convex mirror is the opposite of a concave mirror so if we flip the spoon here we have a convex mirror now if you look at yourself on the convex side of the spoon what do you notice you appear to be smaller but your image is now straight or upright and no matter where you move the spoon the image in a convex mirror is always diminished and upright so this was our quick recap on the three mirrors more details on spherical mirrors coming up later in the video but first let me ask you which types of mirrors are you using in your daily lives I'm using all three types of mirrors everyday if you don't believe me I'll be showing you some clippings from my daily life and you need to be a detective and identify the type of mirror is it a plane mirror concave mirror or a convex mirror are you ready let's start in the morning when I shave which type of mirror am i using the shaving mirror is a concave mirror the face in the mirror is magnified if I flip this mirror there's a plane mirror behind this can you see the difference in magnification between the plane mirror and the concave mirror when I comb my hair which type of mirror am i using this mirror has a flat surface it's a plane mirror when I leave the house and go down in the elevator which mirror does the elevator have it's a plane mirror to save time I can actually comb my hair on the way down while driving the car I use the two mirrors the rearview mirror and the side mirror which types of mirrors are these two mirrors that's right the rearview mirror and the side mirror are examples of convex mirrors because they give a greater field of view there are mirrors kept it road intersections so that you can see the vehicles coming from the other side which type of middle are these that's right convex mirrors so as you can see I'm using all three types of mirrors everyday plane concave and convex mirrors concave and convex mirrors are together called spherical mirrors now do you know why they're called spherical mirrors if I take this ball it has the shape of a sphere now let's imagine the surface of this ball to be shiny like a mirror I wish I had a silver colored ball then it would actually look like a mirror now if I take this knife and I cut the ball here this slice is a curved mirror it's called a spherical mirror since it's come from a sphere if the inside portion is polished it's called a concave mirror if you polish the outside portion it's called a convex mirror an easy way to remember the concave mirror is it's as if you're entering a cave it's a hollow portion so this side is a concave mirror and the opposite side which is bulging is a convex mirror the concave mirror can be represented by this simple diagram where the smooth side is the shiny reflecting surface the side with these small dashed lines is the back of the mirror similarly for the convex mirror the smooth side is the shiny reflecting surface and this side is the back of the mirror now an interesting question is why these mirrors behave differently to understand let's imagine we are throwing a parallel beam of light on all the three mirrors let's start with the plane mirror so if you throw the parallel beam of light can you see that the light rays remain parallel even after reflection next let's try the concave mirror now if you throw the parallel beam of light can you see that the concave mirror converges the light rays to a point the concave mirror is a converging mirror and now let's look at the convex mirror so if you throw the parallel beam again can you see that the convex mirror is diverging the light rays so the convex mirror has a diverging action it's a diverging mirror here's a comparison table of a plane concave and convex mirror now you must be thinking why curved mirrors converge and diverge light rays but a plane mirror does not is it because these laws of reflection hold only for a plane mirror and not for curved or spherical mirrors what do you think the answer is the laws of reflection always hold for both plane and curved mirrors let's take a closer look so if you draw the normals at each of the points of incidence for the light rays the angle of incidence is always equal to the angle of reflection but the concave and convex mirror have converging and diverging action because of their curved shape it's due to their curvature that the light rays reflect in this manner there are some important terms for spherical mirrors for example Paul focus centre of curvature principal axis and so on let's understand these terms with the help of a simple diagram let's start with the concave mirror the center of curvature is the center of the hollow sphere of which the mirror is a part the center of curvature is represented by C the center of the surface of the concave mirror is called the pole represented by P here radius of curvature R is the radius of the sphere the straight line passing through the centre of curvature and the pole is called the principal axis the portion of the mirror where the reflection of light takes place is called the aperture of the mirror represented by M - you remember the concave mirror is a converging mirror if a beam of light that is parallel to the principal axis is incident on the concave mirror after reflection the Rays meet at a point on the principal axis this point is called the focus represented by f the focus is exactly in the center of P and C the focal length F is the distance between the pole and the focus so focal length equals radius of curvature by 2 now let's take a look at the convex mirror center of curvature is the center of the hollow sphere of which the mirror is a part represented by C here note that the centre of curvature of a convex mirror lies behind the mirror the center of the surface of a convex mirror is called the pole represented by P here radius of curvature R is the radius this fear the straight line passing through the center of curvature and pole is called the principal axis the portion of the mirror where the reflection of light takes place is called the aperture represented by mm - here remember the convex mirror is a diverging mirror if a beam of light that is parallel to the principal axis is incident on the convex mirror after reflection the rays appear to diverge from a point on the principal axis this point is called the focus represented by F the convex mirror has a virtual focus since the focus lies behind the mirror the focus is exactly in the center of P and C the focal length F is the distance between the pole and the focus so focal length equals radius of curvature by two let's place the label diagram of a concave and convex mirror on our concept board now that we are done with the concepts are you ready for the top three questions on this topic coming up for you right now friends try solving these questions and let me know your answers and doubts by putting it in the comments below I make a commitment to reply to all your comments as soon as possible so I'm going to disappear and you pause the video here and give these questions a shot I hope the concept of spherical mirrors is super clear to now remember our spoon is both concave and a convex mirror I would also encourage you to look for the different types of mirrors in your daily lives for example do you know the torch has a mirror inside it which type of mirror is that and what about the mirror in your dentist's office or the mirror on the streets and in the street lights do let me know what you find by putting it in the comments below and do remember to subscribe to my youtube channel and follow my facebook page and do check out my website manoj academy.com thanks for watching you