Water in a glass?

Question

If you look through an empty glass at say a digital alarm clock it tells the time the correct way, but if you fill the glass with water and look through it then the display is displayed backwards as it would be in a mirror.

Can anyone tell me why this is and solve and argument thats driving me and my mates crazy !!

Why does the water act like a mirror and make the display read backwards ??

Answer 1

Not like a mirror...



Like a convex lens.

Your observation point is beyond the focal point so you get an inverted image.

Answer 2

This only is true with a cylindrical glass - if the glass were square (or a square bottle like gin) then nada.

The cylinder of water is acting like a fat lens that is thick in the middle and thin at the edges. If you move the glass closer or further it will show changes in size and reversal.

The light rays hitting the curved surface of the water are bent varying amounts. In this case, they actually cross over inside the liquid/lens and hitting the other side are bent back - only the ones bent the right amount reach your eye, producing a reversed image.

If you go to a florist or craft store and get a small spherical bowl and fill it with water, it will reverse both right to left and top to bottom.

The empty does not work because the glass surfaces are parallel on each side of the air and the effect occurs inside with opposite (or different curves) A solid glass ball (or big clear marble) does the same thing as the water bowl.

Answer 3

It's a mixture of a lens effect and also the diffraction of light through water. In effect, you have two lenses here, as the light passes throung the glass twice (i.e on the way into the water, and upon leaving the water)

Answer 4

Physicists measure the bending of light, microwaves and other forms of radiation through a material by its "index of refraction." The bigger a material's index, the slower light travels through it, and the more it "bends," or changes direction when going from one material to a different one. Air, for example, has a refractive index of 1.0 for light; water, 1.3; and glass, about 1.5. This means that a beam of light passing from air to water is deflected in one direction by a certain amount and is deflected by glass by a slightly greater angle in the same direction. This bending, in combination with the curved glass surfaces means the light is bent so as to show a reverse image

Answer 5

I think that the light is defracted (bends ) when it passes the glass with water, remember that although light can pass through, if there are objects in the way, it slows down and turn different.



Like when you walk across a mosh pit, you show down and slightly bend in direction.



:)

Answer 6

It would be the conclave (same as looking at your reflection in a spoon), the water acts as the lense and light is bent, therefore the image you see.....

Answer 7

it is probably not reflection (like a mirror, but refraction, like a lens.

Answer 8

wow! i never realised that, maybe its to do with molecules? lol i have no idea sum Fancy scientific answer.

Answer 9

No idea! sorry

Answer 10

can you say prism