Mirror In Every Tank? Myth? - Page 3

Skavatar

lol i'm actually a Gen Xer
 

Dave125g

Now we really feel old.
 

Ulu

Okay I got as far as Quantum tunneling . . . Now I know why you Millennials write TL DR.
 

Kjeldsen

I've noticed this too. Whenever my frogs interact with their reflection, it's always on the side walls, never the front or back.
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Then again, my quarantine tank is so old that the front glass seems to be obscured by something that I can't even razor off. Two fish desperately trying to see out.
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TheeLadyG

I've noticed this too. Whenever my frogs interact with their reflection, it's always on the side walls, never the front or back.
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Then again, my quarantine tank is so old that the front glass seems to be obscured by something that I can't even razor off. Two fish desperately trying to see out.
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It seems like he's interacting with his reflection but he is actually seeing through the glass, it only looks like a reflection from the outside of the tank. Unless you have painted that side black like the back of a mirror, he's seeing out of the side just the same as you see in the front!
 

Skavatar

It seems like he's interacting with his reflection but he is actually seeing through the glass, it only looks like a reflection from the outside of the tank. Unless you have painted that side black like the back of a mirror, he's seeing out of the side just the same as you see in the front!



"Total internal reflection (TIR) occurs when light originating in the medium of the greater index (in this case, water) hits the interface at an angle greater than the critical angle, which is about 48.8º."
"Critical angle– The least angle of incidence at which total internal reflection takes place. The angle of incidence in a denser medium, at an interface between the denser and less dense
medium, at which the light is refracted along the interface. When the critical angle is exceeded, the light is totally reflected back into the denser medium. "

https://www2.optics.rochester.edu/workgroups/berger/EDay/Optics demonstrations for the classroom.pdf

"If you're the sort of person who enjoys swimming, and can either open your eyes underwater or regularly wear a mask or goggles, you've probably notice that the underside of the surface of a swimming pool or other body of water, looks shiny. If you're in a place with cool marine life, you can even get awesome pictures like this:"

"(from this photography guide site which includes some other awesome examples). So, why do you get this effect?

The key physics here is the idea of refraction, which has to do with the propagation of light through matter. You can talk about this in a particle-like picture, if you want, but it's usually described in terms of waves: light waves entering a material slow down slightly due to their interaction with the material, and as a result, their wavelength gets slightly shorter (you can think of it, loosely, as a given wave "catching up" to the wave in front of it as they hit the boundary). A light wave passing from vacuum into glass sees a reduction in speed to about 2/3rds of the speed of light in vacuum, and the wavelength gets shorter by a corresponding amount-- orangey-red light at 600nm would have a wavelength of around 400nm, like that of violet light in vacuum. This is quantified by a number called the "index of refraction," which is a number greater than 1 for ordinary materials; around 1.5 in the case of glass, about 1.3 in the case of water."

Reflecting, Totally; or Why the Pool Looks Shiny from Underwater | ScienceBlogs

more cool pics Reflections
 

Ulu

Index = 1.7 on my new polycarbonate eyeglasses. Much thinner than glass or acrylics, because they bend the light farther. It doesn't sound like much but glass lenses were twice as thick on me.
 

NanaW

Index = 1.7 on my new polycarbonate eyeglasses. Much thinner than glass or acrylics, because they bend the light farther. It doesn't sound like much but glass lenses were twice as thick on me.

Polycarbonate is the best way glass is thick and too heavy acrylics are a joke sorry I used to be in the biz
 

Ulu

Everything depends on lighting and viewing angle, such that you can have anything from no reflection at all to the complete funhouse mirror effect.
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These guys can see each other...
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Ulu

Polycarbonate is the best way glass is thick and too heavy acrylics are a joke sorry I used to be in the biz
The cost is awful high though, which I believe is why you don't see popular polycarbonate fish tanks.
 

NanaW

The cost is awful high though, which I believe is why you don't see popular polycarbonate fish tanks.

I agree
 

Dave125g

Everything depends on lighting and viewing angle, such that you can have anything from no reflection at all to the complete funhouse mirror effect.
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These guys can see each other...
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Great pictures, and very to the point and easy to understand answer, as to the question is there a mirror, and why.
 

Ulu

Thank you Dave. I didn't actually stick my camera in the tank though. I was just looking through the small end of a long tank.
 

Dave125g

Thank you Dave. I didn't actually stick my camera in the tank though. I was just looking through the small end of a long tank.
Still your answer was correct and easy enough to understand.

I like the scientific explanations about light refraction, but it can get confusing for some.
 

Colleen B

My severum often times tries to fight his reflection in the side of the tank.
 

Dave125g

My severum often times tries to fight his reflection in the side of the tank.
Which brings up another point. For some fish this mirror can be quite stressful, for others( peaceful schooling fish) it's comforting .
 

TheeLadyG

Everything depends on lighting and viewing angle, such that you can have anything from no reflection at all to the complete funhouse mirror effect.
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These guys can see each other...
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again, these photos are being taken from the outside of the tank. The fish in the 'funhouse mirror" is not going to see *any* of those reflections except possibly the one on the bottom. You cannot see what they are seeing unless you are *inside* the tank looking out. Yes, it is a matter of refraction, not reflection.
 

Ulu

I took that particular view because (from the camera's view, not the fish's) both cases are exhibited. If I moved my camera 2" forward thru the glass, the photo wouldn't change, as I'm positioned normal to the end glass.
 

Skavatar

do you notice that both water and glass are both transparent (see through) and yet can reflective (reflect s)?

"At a boundary between two transparent media, light is partially reflected and partially refracted. The ratio of the reflected intensity to the incident intensity is called the reflectance R and the ratio of the transmitted intensity to the incident intensity is called the transmittance T."
Reflection and Refraction
 

Dave125g

The amount of reflection the fish is seeing is based on the angle he/she is looking at the glass and the amount of light on the other side of that glass.

There not seeing as much reflection as we are. In some situations there not seeing any.
 

Ulu

Much of this has to do with the reflectivity of the surrounding room when the tank lights are on & the room lights are off or dim.

I found that if a tank is in a very dark room that doesn't reflect much light back into the tank, the fish are very likely to see their reflections. But I put a large mirror in that same dark room which reflects tank light back to the outside of the tank, that additional light prevents the fish from seeing as many reflections.
 

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