There was a mall near where I lived that had a giant concave mirror. You could walk into it and actually pass through your own reflection. They also had a life-sized concrete hippopotamus, but that's a story for another time.
I think you're correct with the effect you suggest for this situation . However for a flat mirror there is a head scratch conundrum to pose :-" if a mirror reverses left and right then why not also top and bottom ".
@@charlesdickens6706 Well that's just semantics depending on how you define "reversing". But saying a flat mirror reverses an image left to right but not top to bottom doesn't make sense. Imagine if you lie down on you right side facing into a flat mirror. Now will think the mirror is reversing the image top to bottom (because your left side is now the top)? I'd say a flat mirror is not reversing it left to right nor top to bottom. If you could grab your reflection from the mirror's perceived 3D space and superimpose it over your physical self in actual 3D space, the face of the mirror you would be poking out the back of your head but your left arm would still be intersecting with its reflected self. So the image is being reversed front to back.
I was having a mental breakdown earlier from trying to imagine a concave mirror using only some text, and now i understand it all perfectly. Thank you for this demonstration.
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
what I find more fascinating(sort of...it's really kinda of the same thing...but try and follow lol) than the ball switching, is the fact that the mirror can have both types of reflections simultaneously e.g. when the ball is close to the mirror it is "correctly" reflected, but the chairs and cameras further off are upside down.
I can't stop watching this video, the more I watch, the more I get to understand the sketches in my textbook. Sir, I thank God I found a teacher like you!
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
This confused me bc the mirror is 360’ What about the effect on the left and right? This must also switch, but the ball is only divided 180’. I would like to se this demo with four color patterns divided in fourths. My imagination tells me that the ball’ reflection will appear to spin?
Would be interesting to see, don't think you'd get a spinning effect though, might even be if you imagine every line you could draw from the centre of a circle to the edge (cross section of the ball), every line might actually be effectively mirrored in a perpendicular plane that passes through the centre of the circle, so on a clock face the 1 and 7 would switch places, and 10 would swap with 4 etc, due to all the spherical curvature going on with the mirror and ball, in this case all the imaginary lines in the top half of the circle get mirrored across the centre into the bottom and vice versa causing an apparent vertical mirroring effect, when it's actually a circular mirroring across all angles which as I write this I realise would give the same end result of a simple horizontal+vertical mirroring. But what ever would happen I think it would still happen suddenly as it passed back and forth through that middle point rather than looking like it is spinning. After thinking about it that much I definitely want to see it also
You get reflection symmetry through a _point._ Looking head-on, each point on the edge of the ball gets reflected to a point on the opposite side of the ball. (Technically, you get reflection symmetry through the point at the center of the disk defined by looking at the ball head-on, which is the same as saying "the image of the ball _projected_ onto a 2D plane normal to our line of sight.) So to answer your question: No, you wouldn't see spinning. Imagine a ball with 4 colors: red, yellow, green, blue, say, going clockwise, starting with red on the top right of the ball. In the reflection when the ball is far from the concave mirror, you'd see green, blue, red, yellow. Fun fact: it turns out reflection through a point in a 2D plane is equivalent to two reflections across orthogonal lines (e.g., reflecting across the x-axis and then y-axis, in either order). Fun fact 2: reflection through a point in a 2D plane is equivalent to a 180° rotation. *Note*, however, that you wouldn't see _any spinning,_ as this "rotation" is just the operation that you imagine to map the colors on the ball to the location of the colors in the reflection. In some sense, the "rotation" happens the instant the ball crosses the focal point and the image switches instantly to its "rotated" version. Hope this helps. Sorry if the words are confusing-I tried to keep everything clear.
When the ball is further away from the mirror than the focal point, the concave mirror should form a real image as the same side of the ball. How are we able to see that image in this video? Or what exactly are we seeing when we see the ball is on this side of the focal point?
Interesting - do the red and blue areas when the ball is at the focal point reveal anything about deviations in the mirror's shape? Kind of thinking about the Foucault method of grinding parabolic reflectors for telescopes.
I wonder what would happen in a hypothetical perfect mirror. I imagine it would get bigger and bigger until it reaches a infinitely small point before switching ?
@@danilooliveira6580 The image is still a one to one representation. It appears bigger because the entire area of the mirror is reflecting a smaller section of the ball but is not enlarging any one section of the ball!
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
What i find interesting about this demonstration is that this is a great example of what a 4th or 5th dimensional object would look like passing through our 3rd dimension
Yeah, it's weird. We used to live in a world where we'd comment that the CGI was "looking almost real". Now we comment that our reality "looks almost CGI". We're losin' it, a little more every day. 😬☹️
@DogMan Haha.. I was going to throw a flat earth comment in as well.. But... I saw this and thought I'd just laugh instead (and write a short comment that actually got progressively longer as I decided to explain myself)
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
When the image is inverted, it is a Real image. so how can we see it on the mirror?, pls don't say that my eyes are not right... I have searched this on many platforms and asked 1-2 teachers about this and my doubt has not been cleared until now. Thanks
Nitin K raised another question: Can we see the real image at different angles, or we can see it only straight in front of the mirror? Answer: When forming a real image on a screen, the image will be in a certain location on the screen. If the object is centered in front of the mirror, the real image will be centered on the screen. If the object is not centered, the image will not be centered either.
Thanks a lot sir for explaining it in a very interesting way. But I have one question that I do not understand for a long time. As far as I know we can not see real image until we project them on a screen. Also we know concave mirrors produce real image when object is placed more than focal point. So how we are able to see the image within the mirror without projecting it on a screen ?
That is kind of redundant saying. They don't need to be from infinity. You can get parallel rays by having, let's say, an array of laser pointers. The point is, when you have a normal source of light (bulb, candle,...) at non-infinity, the rays go from its center in all directions. If you have a distant source (like the Sun), it still goes in all directions from the Sun, but the rays hitting your location are almost parallel. If the source is in infinity, it would be truly parallel...
The thing is, it works also in the opposite way - parallel rays converge to the focal point (that is how the parabolic antenna works, the dish focuses the signal to the small receiver), but if the light source IS in the focal point, the reflected rays will be parallel (that is how some car lights work)
Very informative demonstration. A possibly useful supplement would be to have a series of graphics plotting the path that the light takes at the different points in the movement of the ball, as it might help students understand why the reflection inverts. Thanks for posting.
British Gas once had a demonstration of a large concave mirror with a white hot limestone ball floating on a powerful gas flame. You viewed it from one spot and saw a vast (virtual) white hot 'Sun' slowly rotating, filling your field of view. (The roaring gas torch added to the drama!)
Woah! Do you know where I can view this? Is there footage online? That seems like something I'd pay to see in person. MOSI the Museum Of Science and Industry has some really cool demos like that, such as a huge indoor tornado simulator and a massive fire vortex, but nothing like what you described.
@@DanteYewToob I have looked for it without success. I think it was an exhibit in a Hultons Boys & Girls Exhibition in Olympia London in the 50s or 60s (I am in my 70s) These were created to encourage interest in Science & Technology (worked for me!)
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
A very good demo... Is the inverted image formed inside the mirror real or virtual. real images are formed when reflected rays from the mirror actually meet and virtual images are formed when reflected light rays appear to meet ..So the can the inverted image be got on the screen kept infront ?
Can we place a screen at the center of curvature to obtian the real image,but then we will see two images one on the glass and second on the screen how's it possible
When the ball is close to the mirror the upper portion of the mirror can only focus on and reflect the upper portion of the ball, when the ball is further away the upper portion of the mirror is focused on and reflecting the lower portion of the ball and vice versa!
@@physicsdemos Hello sir, I have a question. I don't have a double sided mirror at home. But is the front side of the mirror concave and its opposite a convex? Or its front a plane mirror while its opposite side a concave?
@@xyz-vl8ri Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
So, the image is real between the pole and just ahead of the focus and virtually behind the focus? Also, what is infinity in mirrors? Thanks for the videos by the way, very helpful. -Asmi
Asmi, I'm glad the videos are useful to you. The image is virtual when the object is inside of the focal point, and real when the object is outside of the focal point. Through the mirror, you can see both real and virtual images, as shown in the video. The difference is that when the object is outside of the focal point, you could also see the image on a screen, that is, you could put a screen in the image plane and see the image, if the object is bright enough.
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
@@boydedwards5475 Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
If rays from the center of curvature bounce back to that point, does that mean that an object at that point would then be invisible from any perspective that doesn't view the mirror through that point?
Can Anyone please tell me why the real image is formed on the mirror? It should be on the respective position. For example-If an object is between C and F, then image should be Beyond C, then why actually it's formed inside the mirror? Please clear this doubt of mine.
Sir as you moved ball away from the mirror in between pole and Focal point then image is still forming in the mirror and its is still looks real, erected and enlarged but I studied when Object is placed between Pole and focal point imagae is formed beyond the mirror that is virtual and erected. Please explain Sir how it is possible ?
I was hoping to see if the ball were swung side to side or parallel to the mirror if you would achieve the same or different effect. Thomas M. Dutkiewicz
Another physics demo is conservation of energy where you hold the ball right next to the mirror and release it and it swings back and will never hit it.
If u mess this one up, u could just use that as your inelastic collision demo, as the mirror steals all the ball's energy when it shatters. Then just rewrite your lectures a bit to work some Newtonian physics into your optics class and ur set.
This demo has all to do with the tangent function. It's part of how the thin lens equation is derived. Similar triangles and all that. The image goes to and fro infinity. Negative infinity too. It's amazing.
i studied optic for like 10 times but never get to see it in reality. dude thats like magic and its facinating. i never understood the consept of "virtual and real" image. once i saw this it started to makes sense. while the ball swings it looks like the ball coming from behind of the mirror and after a point (f point) it looks like the image switches dimensions and actually swing toward you. its crazy to me.
Yes, but you'll never be EXACTLY at the focal point. Just inside the focal point, the image is enormous and upright, and just outside the focal point, the image is enormous and inverted. So for all intents and purposes, the image near the focal point will be huge. Note also that near the focal point, any imperfections in the mirror, or any amount of being off axis, will distort the image.
Sunitha, the image is virtual when the object is inside of the focal point, and real when the object is outside of the focal point. Through the mirror, you can see both real and virtual images, as shown in the video. The difference is that when the object is outside of the focal point, you could also see the image on a screen, that is, you could put a screen in the image plane and see the image, if the object is bright enough.
*If the object is on focal point in concavity mirror that mean* *Position of the object at focal Position of the image at the infinity* ♾️ *Size of the image -highly inlarge* *Nature of the image -real and inverted* *Answer by indian 🇮🇳 student*
but the terminologies virtual and real in the textbooks made me confused. Can they come up with another terminologies that seem understandable even by elementary students?
Crazy how you can have a single reflection on a concave surface but multiple different objects in the reflection which are different orientations. When the ball is close enough to the inside of the mirror, it is upright while the background is inverted.
11 หลายเดือนก่อน
Would it be possible to know the characteristics of your mirror, or to have the name of the supplier please. I tried with my concave mirror but it doesn't give results as good as you
Hello sir I have a question. I don't have a double sided mirror at home. But is the front side of the mirror concave and its opposite is convex? Or is its front a plane mirror while its opposite side is a concave?
Hi, If anyone is interested, I published a book called "Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
So I have a question. Aren't the images when object is placed beyond the focus real and required to be taken on a screen? How are they visible in the mirror?
Now how about an encapsulated* (not sure if that's the right word lol) mirror? Is it that same effect in every direction? Like a mirage horizon that follows your vision? How much does depth perception play in that?
The intensity of the light to an observer from a source is inversely proportional to the square of the distance from the observer to the source. This shows that as the distance from a light source increases, the intensity of light is equal to a value multiplied by 1/d2.
So a blackhole bends the light and what you can see on the edge just before the light gets devoured is actually on the opposite site and curved? And what does this in mean in comparison to the camera obscura?? I’ve got allot more questions know…
Someone, please answer this. In the video the ball starts at the top of the mirror, then travels down, through the focal point then up again to be in almost a direct line in height to where the ball started, parallel to the floor. My question is: what would you see in the mirror it the ball continued to move towards the floor to point below the focal point the same distance out and down as where the ball started up and behind the focal point? Will the colour of the reflection remain the same as in the video or would it remain the same as the ball itself?
For real images (concave mirror), all reflecting rays are meeting at the front of the mirror. Then how image of the object is visible at the back/beyond of the mirror.
I have one question. Concave mirror form a real image means the image form in front of it and we need a screen to see it. But in that demonstration the image is formed inside the mirror. Can someone please explain where i lack understanding.
Yes, of course. Sure for the optics portion of physics we did convex n concave mirrors and lenses but we may have overlooked this little detail or some of us . Here's something else :- I'm longsighted so I don't need specs for driving but a decade ago I noticed that to see objects clearly in my convex rear vision side mirror I needed to wear the reading spectacles , not immediately but eventually the penny dropped , it's cos I was viewing a virtual image rather than a reflection in the manner we are used to with flat mirrors. The virtual image being equivalent to two feet from my eyes instead of a hundred metres away say for the actual object. There's a phantom image position that can be traced somewhere behind mirror by following the convergence of light rays . Another optics phenomenon is with polarising filters . It's more a paradox that occurs when messing with three filters. There may be one or two good videos about it . John Gribbin in his book Schrödinger's Kittens leads into quantum theory from the paradox .
If you own a Movado watch with the museum face then you have one of these at 12 o'clock. A perfectly polished little concave mirror that is amazing under high magnification.
I hv a doubt, if the image formed by a concave mirror is real and on the same side of the object we shud not be able to see the image on the mirror ryt?
Our brain just adapt. Some dudes used a vr headset and displayed an image of their real time surrounding but upside down, after a while, their brains adapted pretty well. And when they took it off, they had the impression that the world was upside down.
![ตีสิบเดย์ [FULL] | เปิดใจ "อาจารย์ เบียร์ ฅนตื่นธรรม" นักสนทนาธรรมสายดุดัน!](http://i.ytimg.com/vi/vqaBI_mnoDk/mqdefault.jpg)
There was a mall near where I lived that had a giant concave mirror. You could walk into it and actually pass through your own reflection. They also had a life-sized concrete hippopotamus, but that's a story for another time.
🦛
Did it spray concrete shit everywhere?
Ohhh! I want that story now!
@@emceeboogieboots1608 If you insist. It was a life-sized concrete hippopotamus. Little kids liked to sit on it. (I never said it was a good story.)
@@DavidLS1 in the future, if I ever feel I’ve disappointed someone, I can always say: At least I didn’t use that hippopotamus story 😀
I discovered this phenomena as a little kid at the dining table, viewing myself in a spoon
You swing your balls in front of a spoon at the dining table??
There is no spoon.
Yup, all these guys get PhDs for doing stuff we figured out as kids
@@seanfaherty , and getting paid to do it!
*phenomenon
These Pepsi ads are getting smart day by day
thought the same. lol
Boy, that was clever.
Generation next?
are getting smart-er? Yeah!
No, your the Pepsi Rep.
The ball should have four colors so you could see it reversing the image left to right.
actually u can notice it e.g. @2:22.
Also, it only happens when the object distance is larger than the focal length.
I think you're correct with the effect you suggest for this situation . However for a flat mirror there is a head scratch conundrum to pose :-" if a mirror reverses left and right then why not also top and bottom ".
@@charlesdickens6706 Well that's just semantics depending on how you define "reversing". But saying a flat mirror reverses an image left to right but not top to bottom doesn't make sense. Imagine if you lie down on you right side facing into a flat mirror. Now will think the mirror is reversing the image top to bottom (because your left side is now the top)? I'd say a flat mirror is not reversing it left to right nor top to bottom. If you could grab your reflection from the mirror's perceived 3D space and superimpose it over your physical self in actual 3D space, the face of the mirror you would be poking out the back of your head but your left arm would still be intersecting with its reflected self. So the image is being reversed front to back.
@@charlesdickens6706 A flat mirror doesn't reflect left and right. It's our brain that expects that it should.
@@charlesdickens6706 You're the one reflecting it that way, not the mirror.
I was having a mental breakdown earlier from trying to imagine a concave mirror using only some text, and now i understand it all perfectly. Thank you for this demonstration.
Me too lol I couldn't even think how it is possible that there is no image when the object is on the focus point, until now.
you can try this at home by looking at spoon
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
Hope that by now you realized you can google up stuff BEFORE you have a mental breakdown trying to imagine it...
Text?
what I find more fascinating(sort of...it's really kinda of the same thing...but try and follow lol) than the ball switching, is the fact that the mirror can have both types of reflections simultaneously e.g. when the ball is close to the mirror it is "correctly" reflected, but the chairs and cameras further off are upside down.
Exactly
I can't stop watching this video, the more I watch, the more I get to understand the sketches in my textbook. Sir, I thank God I found a teacher like you!
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
I love the fact that when the ball is close to the mirror, it's not inverted, but the everything else in the mirror is.
They should use simple "real-time" optical demos like this to prime students to learn Geometry basics.
3blue1brown
This confused me bc the mirror is 360’ What about the effect on the left and right? This must also switch, but the ball is only divided 180’. I would like to se this demo with four color patterns divided in fourths. My imagination tells me that the ball’ reflection will appear to spin?
Very good point,i imagine so too.
Would be interesting to see, don't think you'd get a spinning effect though, might even be if you imagine every line you could draw from the centre of a circle to the edge (cross section of the ball), every line might actually be effectively mirrored in a perpendicular plane that passes through the centre of the circle, so on a clock face the 1 and 7 would switch places, and 10 would swap with 4 etc, due to all the spherical curvature going on with the mirror and ball, in this case all the imaginary lines in the top half of the circle get mirrored across the centre into the bottom and vice versa causing an apparent vertical mirroring effect, when it's actually a circular mirroring across all angles which as I write this I realise would give the same end result of a simple horizontal+vertical mirroring. But what ever would happen I think it would still happen suddenly as it passed back and forth through that middle point rather than looking like it is spinning. After thinking about it that much I definitely want to see it also
He demoed this with his hand at 0:29 and 1:07 :-)
@@biancabonet Maybe if I could find a little LSD after 35 years? Lol.
You get reflection symmetry through a _point._ Looking head-on, each point on the edge of the ball gets reflected to a point on the opposite side of the ball. (Technically, you get reflection symmetry through the point at the center of the disk defined by looking at the ball head-on, which is the same as saying "the image of the ball _projected_ onto a 2D plane normal to our line of sight.)
So to answer your question: No, you wouldn't see spinning. Imagine a ball with 4 colors: red, yellow, green, blue, say, going clockwise, starting with red on the top right of the ball. In the reflection when the ball is far from the concave mirror, you'd see green, blue, red, yellow.
Fun fact: it turns out reflection through a point in a 2D plane is equivalent to two reflections across orthogonal lines (e.g., reflecting across the x-axis and then y-axis, in either order).
Fun fact 2: reflection through a point in a 2D plane is equivalent to a 180° rotation. *Note*, however, that you wouldn't see _any spinning,_ as this "rotation" is just the operation that you imagine to map the colors on the ball to the location of the colors in the reflection. In some sense, the "rotation" happens the instant the ball crosses the focal point and the image switches instantly to its "rotated" version.
Hope this helps. Sorry if the words are confusing-I tried to keep everything clear.
When the ball is further away from the mirror than the focal point, the concave mirror should form a real image as the same side of the ball. How are we able to see that image in this video? Or what exactly are we seeing when we see the ball is on this side of the focal point?
Same doubt
same Q, have you found the answer?
I was amazed by optical physics in school. Amazed someone a long time ago would sit down and figure out the math.
Demonstrations are sometimes all that is needed to get something. Brilliant!!!!
Interesting - do the red and blue areas when the ball is at the focal point reveal anything about deviations in the mirror's shape? Kind of thinking about the Foucault method of grinding parabolic reflectors for telescopes.
No concave or convex mirror has a perfect arc or evenness, especially a cheap one like this!
yes the focal point, itd be like a microscope, every defect of the less-than-perfect mirror surface magnified.
If you make the mirror as near to perfect as you can then any remaining distortions are due to defects in the ball surface.
I wonder what would happen in a hypothetical perfect mirror. I imagine it would get bigger and bigger until it reaches a infinitely small point before switching ?
@@danilooliveira6580
The image is still a one to one representation. It appears bigger because the entire area of the mirror is reflecting a smaller section of the ball but is not enlarging any one section of the ball!
This gives me such an intuitive understanding after reading my textbook and dozens of TH-cam videos
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
From this prospective I can imagine myself beeing inside an eye giving the information straight to the brain. Nice one.
This guy's voice is too soothing. I could never learn anything from him. I'd be in a trance!
My hs history teacher looked and sounded like this guy, I don't think I was awake for 1 class 😅
I would have majored in physics if I saw these videos when I was 16-18! Bravo!
Ooh, with a suitably accurate sphere (of 2 colours) you've got yourself a cool way of checking the mirror shape.
What i find interesting about this demonstration is that this is a great example of what a 4th or 5th dimensional object would look like passing through our 3rd dimension
Good way to figure out whos stoned in class
Woah, dude!
By the looks of it, no one is in class, probably because all the seats are upside down. They must all be in a heap of the ceiling.
😂😂😂 Not saying I'm stoned, but I would've loveddd to see like 185 more seconds of that ball going back and forth and back and forth at the end....
@@kaylor87 i am stoned and i approve
@@maximeduchalet4662 😂😂
The images when the ball was in motion looked so CGI-ed🤩
Yeah, it's weird.
We used to live in a world where we'd comment that the CGI was "looking almost real".
Now we comment that our reality "looks almost CGI".
We're losin' it, a little more every day.
😬☹️
@DogMan Haha.. I was going to throw a flat earth comment in as well.. But... I saw this and thought I'd just laugh instead (and write a short comment that actually got progressively longer as I decided to explain myself)
Optics is the best! This is a concise explanation with no math. Hopefully it gets people interested :)
very interesting and wow....excellent experiment shown by an excellent teacher. 👍👍
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
When the image is inverted, it is a Real image. so how can we see it on the mirror?, pls don't say that my eyes are not right... I have searched this on many platforms and asked 1-2 teachers about this and my doubt has not been cleared until now. Thanks
I'm not even going to bother with an intelligent and well thought out comment. I'm just going to say "Wow! That's so cool dude".
4 years ago... why did it take so long! This is awesome
Sometimes newcomers in TH-cam update algorithm slightly, then TH-cam end up showing old videos ;)
Nitin K raised another question: Can we see the real image at different angles, or we can see it only straight in front of the mirror? Answer: When forming a real image on a screen, the image will be in a certain location on the screen. If the object is centered in front of the mirror, the real image will be centered on the screen. If the object is not centered, the image will not be centered either.
Sir I asked," A real image WITHOUT A SCREEN can be seen from other angles or can be only seen from straight in front of the mirror ? "
Anyway my doubt has been cleared sir.Thank you very much sir for clearing my doubts.You are a wonderful teacher.
Without a screen, you can see the image from a variety of locations, not just on the axis.
Yes sir.
I really want to know how the moon reflects himself equal from all sides of the plane
Thanks a lot sir for explaining it in a very interesting way. But I have one question that I do not understand for a long time. As far as I know we can not see real image until we project them on a screen. Also we know concave mirrors produce real image when object is placed more than focal point. So how we are able to see the image within the mirror without projecting it on a screen ?
the retina of the eyes of we the observers, are the screens. The light rays from the real image arrive on the retina (screen) of our eyes.
All schools need to have this.
It is much more interesting when we practically see it.
"Parallel rays that come from infinity"
I've never heard this phase and am highly intrigued.
That is kind of redundant saying. They don't need to be from infinity. You can get parallel rays by having, let's say, an array of laser pointers.
The point is, when you have a normal source of light (bulb, candle,...) at non-infinity, the rays go from its center in all directions.
If you have a distant source (like the Sun), it still goes in all directions from the Sun, but the rays hitting your location are almost parallel. If the source is in infinity, it would be truly parallel...
The thing is, it works also in the opposite way - parallel rays converge to the focal point (that is how the parabolic antenna works, the dish focuses the signal to the small receiver), but if the light source IS in the focal point, the reflected rays will be parallel (that is how some car lights work)
Very informative demonstration. A possibly useful supplement would be to have a series of graphics plotting the path that the light takes at the different points in the movement of the ball, as it might help students understand why the reflection inverts. Thanks for posting.
The concave mirror with a pendulum. Otherwise known as instant migraine mirror.
British Gas once had a demonstration of a large concave mirror with a white hot limestone ball floating on a powerful gas flame. You viewed it from one spot and saw a vast (virtual) white hot 'Sun' slowly rotating, filling your field of view. (The roaring gas torch added to the drama!)
Woah!
Do you know where I can view this? Is there footage online?
That seems like something I'd pay to see in person.
MOSI the Museum Of Science and Industry has some really cool demos like that, such as a huge indoor tornado simulator and a massive fire vortex, but nothing like what you described.
@@DanteYewToob I have looked for it without success. I think it was an exhibit in a Hultons Boys & Girls Exhibition in Olympia London in the 50s or 60s (I am in my 70s) These were created to encourage interest in Science & Technology (worked for me!)
Amazing demonstration and clear explanation thanks you so much I was studying and dont quite get how it would look like but now I know!
Thank you sir for this. Simple but great explanation!🙏
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
This is really interesting. Is this experiment copyrighted?
Is it okay to upload a video of the same experiment in Japan?
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
Excellent explanation with a two color ball. Worth to share.
If you were my science teacher I would have been a scientist 👍
That's how every optics class should be taught! Thanks a lot!
A very good demo...
Is the inverted image formed inside the mirror real or virtual. real images are formed when reflected rays from the mirror actually meet and virtual images are formed when reflected light rays appear to meet ..So the can the inverted image be got on the screen kept infront ?
Same doubt
How's the real image formed in the mirror?
Same question
The light rays hitting the mirror bounce off and converge and then diverge. This is a real image because the light actually converges. (>
Can we place a screen at the center of curvature to obtian the real image,but then we will see two images one on the glass and second on the screen how's it possible
Bro I have the same question ? I am so confused.
When the ball is close to the mirror the upper portion of the mirror can only focus on and reflect the upper portion of the ball, when the ball is further away the upper portion of the mirror is focused on and reflecting the lower portion of the ball and vice versa!
very cool. you should've make more of these short and informative videos (:
Thanks!
@@physicsdemos Hello sir, I have a question. I don't have a double sided mirror at home. But is the front side of the mirror concave and its opposite a convex? Or its front a plane mirror while its opposite side a concave?
@@xyz-vl8ri Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
So, the image is real between the pole and just ahead of the focus and virtually behind the focus? Also, what is infinity in mirrors? Thanks for the videos by the way, very helpful. -Asmi
Sorry, I mean virtual
Asmi, I'm glad the videos are useful to you. The image is virtual when the object is inside of the focal point, and real when the object is outside of the focal point. Through the mirror, you can see both real and virtual images, as shown in the video. The difference is that when the object is outside of the focal point, you could also see the image on a screen, that is, you could put a screen in the image plane and see the image, if the object is bright enough.
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
@@boydedwards5475 Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
If rays from the center of curvature bounce back to that point, does that mean that an object at that point would then be invisible from any perspective that doesn't view the mirror through that point?
TH-cam at it again with these recommendations.
Can Anyone please tell me why the real image is formed on the mirror? It should be on the respective position. For example-If an object is between C and F, then image should be Beyond C, then why actually it's formed inside the mirror? Please clear this doubt of mine.
same Q, have you found the answer?
Sir as you moved ball away from the mirror in between pole and Focal point then image is still forming in the mirror and its is still looks real, erected and enlarged but I studied when Object is placed between Pole and focal point imagae is formed beyond the mirror that is virtual and erected.
Please explain Sir how it is possible ?
I was hoping to see if the ball were swung side to side or parallel to the mirror if you would achieve the same or different effect.
Thomas M. Dutkiewicz
VSAUCE once did a video on being inside a spherical mirror but it was quite hard to imagine. Now we have the perfect example
Yeah that seems like an interesting explanation and all but can you get on already with bouncing the ball back and forth on the pretty mirror?
If I were the teacher, this would be a demo of how to break a mirror.
Another physics demo is conservation of energy where you hold the ball right next to the mirror and release it and it swings back and will never hit it.
If u mess this one up, u could just use that as your inelastic collision demo, as the mirror steals all the ball's energy when it shatters. Then just rewrite your lectures a bit to work some Newtonian physics into your optics class and ur set.
This demo has all to do with the tangent function. It's part of how the thin lens equation is derived. Similar triangles and all that. The image goes to and fro infinity. Negative infinity too. It's amazing.
i studied optic for like 10 times but never get to see it in reality. dude thats like magic and its facinating. i never understood the consept of "virtual and real" image. once i saw this it started to makes sense. while the ball swings it looks like the ball coming from behind of the mirror and after a point (f point) it looks like the image switches dimensions and actually swing toward you. its crazy to me.
Theoretically if you put an object exactly in the focal point the image disappear. So why is the image "huge" instead of non existent?
Thanks.
Yes, but you'll never be EXACTLY at the focal point. Just inside the focal point, the image is enormous and upright, and just outside the focal point, the image is enormous and inverted. So for all intents and purposes, the image near the focal point will be huge. Note also that near the focal point, any imperfections in the mirror, or any amount of being off axis, will distort the image.
Understood. Thank you.
It's interesting how the theory works in in practice.
But why do we see a vertual image .... Shouldn't we see a real image that is obtained on a screen...🤔
Sunitha, the image is virtual when the object is inside of the focal point, and real when the object is outside of the focal point. Through the mirror, you can see both real and virtual images, as shown in the video. The difference is that when the object is outside of the focal point, you could also see the image on a screen, that is, you could put a screen in the image plane and see the image, if the object is bright enough.
Amazing, thanks for replying
0:45 can someone explain me what happens when the object is at the focal point please?
*If the object is on focal point in concavity mirror that mean*
*Position of the object at focal
Position of the image at the infinity* ♾️
*Size of the image -highly inlarge*
*Nature of the image -real and inverted*
*Answer by indian 🇮🇳 student*
Who's that guy Infront of you standing on the ceiling?
but the terminologies virtual and real in the textbooks made me confused. Can they come up with another terminologies that seem understandable even by elementary students?
Show this to someone who is "tripping balls" off of some hallucinogen and make their mind exploded.
So why isn't this yourself?
Crazy how you can have a single reflection on a concave surface but multiple different objects in the reflection which are different orientations. When the ball is close enough to the inside of the mirror, it is upright while the background is inverted.
Would it be possible to know the characteristics of your mirror, or to have the name of the supplier please. I tried with my concave mirror but it doesn't give results as good as you
Can this be used to cook food by solar sun rays which will be focusing on that focal point
Google "Walkie Talkie building London" which was known to MELT cars
This really helped me grasp the concept well. Thank you so much.
So... y do u think that the background image look the same... and not flipped throughout the curvex of the mirror ?
My brain just died by seen the ball moving! It's insane, love it!
Sir I have a question. If the image formed by a concave mirror if formed infront of the mirror why do we see it on the mirror.
Excellent demonstration....thank you so very much
Hello sir I have a question. I don't have a double sided mirror at home. But is the front side of the mirror concave and its opposite is convex? Or is its front a plane mirror while its opposite side is a concave?
Is it possible to have a microscope that works with a concave mirror instead of glass lenses?
The pendulum motion in the last was about to faint me🙄😂
Hi,
If anyone is interested, I published a book called
"Making Technique for Large Diameter Concave Mirror, Convex Mirror, and Thin-Sided Lens" on Rakuten Kobo E-Book platform. In the book, molding silicone, clear epoxy (or clear plastic resin), polyurethane, air pumping tool, air vacuum tool, wood chips, acetate paper, etc. I mentioned the methods that will allow you to produce meters of diameter using. In this way, you will have the knowledge and experience that you can carry out your projects for astronomy and solar energy in a practical way. Have a nice day.
@@alihaydartunc7249 is everything ok at home fr tho 🌚😅😂
So I have a question. Aren't the images when object is placed beyond the focus real and required to be taken on a screen? How are they visible in the mirror?
No one searched for this video. It's TH-cam's way of telling you to go to bed.
um... so you see...
Thanks, now I know why things are upside down in my reflector telescope. Good demo.
Now how about an encapsulated* (not sure if that's the right word lol) mirror? Is it that same effect in every direction? Like a mirage horizon that follows your vision? How much does depth perception play in that?
I have little confusion...Why real image is formed on the other side of mirror.
same Q, have you found the answer?
The intensity of the light to an observer from a source is inversely proportional to the square of the distance from the observer to the source. This shows that as the distance from a light source increases, the intensity of light is equal to a value multiplied by 1/d2.
What in the actual fuck did I just see? That was amazing on so many levels.
What happens if you say "Bloody Mary" 3 times in front of this mirror?
At first glance of your thumbnail, all I could think of is "Hey, that's the Dr Theopolis prop from Buck Rogers"
How are we able to see the image which is real without the use of screen ?
As i know concave mirror forms real image when the object is beyond focus
So a blackhole bends the light and what you can see on the edge just before the light gets devoured is actually on the opposite site and curved? And what does this in mean in comparison to the camera obscura?? I’ve got allot more questions know…
How real images can be caught in mirror?
When the two ray of light actually meet
Try to do the experiment yourself. Use a frying pan which has reflective surfaces, a 🕯️ and a cardboard as a screen.
I just woke up 4 years later, having been hypnotized.
We've been hypnotized.
Someone, please answer this. In the video the ball starts at the top of the mirror, then travels down, through the focal point then up again to be in almost a direct line in height to where the ball started, parallel to the floor.
My question is: what would you see in the mirror it the ball continued to move towards the floor to point below the focal point the same distance out and down as where the ball started up and behind the focal point?
Will the colour of the reflection remain the same as in the video or would it remain the same as the ball itself?
For real images (concave mirror), all reflecting rays are meeting at the front of the mirror. Then how image of the object is visible at the back/beyond of the mirror.
same Q bro, did you got the answer?
I have one question. Concave mirror form a real image means the image form in front of it and we need a screen to see it. But in that demonstration the image is formed inside the mirror. Can someone please explain where i lack understanding.
Now use this information once in your life
Isn't this just like how images are formed in the retina?
This effect is due to the mirror's focal point rather than a lensing effect!
Ur mirror is very clean and clear 👌👌
Wait. What happens if you swing the ball side to side?
That was good, but what is the function of it. 👍👍
Yes, of course. Sure for the optics portion of physics we did convex n concave mirrors and lenses but we may have overlooked this little detail or some of us . Here's something else :- I'm longsighted so I don't need specs for driving but a decade ago I noticed that to see objects clearly in my convex rear vision side mirror I needed to wear the reading spectacles , not immediately but eventually the penny dropped , it's cos I was viewing a virtual image rather than a reflection in the manner we are used to with flat mirrors. The virtual image
being equivalent to two feet from my eyes instead of a hundred metres away say for the actual object. There's a phantom image position that can be traced somewhere behind mirror by following the convergence of light rays .
Another optics phenomenon is with polarising filters . It's more a paradox that occurs when messing with three filters. There may be one or two good videos about it . John Gribbin in his book Schrödinger's Kittens leads into quantum theory from the paradox .
If you own a Movado watch with the museum face then you have one of these at 12 o'clock. A perfectly polished little concave mirror that is amazing under high magnification.
I don't understand! Can you please explain it in a mathematical equation?
Does this have anything to do with fake moon landing? I’m sure I could shoehorn it in somehow
I hv a doubt, if the image formed by a concave mirror is real and on the same side of the object we shud not be able to see the image on the mirror ryt?
Great camera work! Jeezus!
I'm glad our concaved surface of the retina doesn't flip our vision after some focal point. There again- I wonder why not?
It does
Our brain just adapt.
Some dudes used a vr headset and displayed an image of their real time surrounding but upside down, after a while, their brains adapted pretty well. And when they took it off, they had the impression that the world was upside down.
Who is the guy standing on his head in the audience?
Wasn't there a Ray Bradbury short Story about the Hall of Mirrors at a fairground?