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Old Oct 27th 2018, 07:50 AM   #1
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Join Date: Sep 2018
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The mangifying glass

When the light go throw a object that reflect a light and magnifying class it show the object bigger.
Why the object become bigger? What happen in the atoms and molecules of the glass when the light pass throw it?
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Old Oct 28th 2018, 05:47 AM   #2
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Light goes slower through glass than through air or a vacuum. Some people prefer to say that light does NOT slow down- it moves at c through the vacuum between the atoms, is captured by an atom then released- but the result is that, overall, light takes a longer time to go through glass. Now imagine a light wave striking glass at an angle. One end of the wave hits the glass first and slows down before the other. The part already in the glass moves a shorter distance than the rest so the wave "bends". Of course, with a flat piece of glass the opposite happens as the light wave comes out of the glass so the wave winds up going on at exactly the direction it had before entering the glass.

With a curved piece of glass, it is a different situation! The different parts of to the wave spend different lengths of time in the glass, at the lower speed, so that the wave comes out of the glass at different angles. A lens is specifically shaped to focus the light: All of the light coming through the lens is directed through the "focal point" of the lens. If you look at an object within the "focal length" of the lens (so closer to the lens than the focus) it will appear larger.

One way to think about this: Draw a line segment on a sheet of paper representing the lens (actually the central plane of the lens). Mark two points, one on either side of the "lens", at the same distance from the lens, representing the focal points. Now draw an "arrow" (a line segment with different marking at top and bottom). Draw a line from the top of the arrow perpendicular to the lens. Continue it on the other side as a line going through the focus. Draw a second line from the top of the arrow through the focus on this side to the lens. Continue it on the other side of the lens going out perpendicular to the lens. Where those two lines meet is where the "image" of that end of the arrow will be. Do the same with the other end of the arrow to find its image. The image of the arrow itself will be the line between those two points.

Experiment with having the "arrow" inside or outside the focal point to see what happens to the image.
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