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Ever Wondered How a Typical Mirror Works?

Mirror work tutorial,mechanical mirror works,mirror works detail

What is a mirror? It is something that reflects (throws back) your image. Now, this reflection is possible only when there is light (sunlight or artificial light). Try standing in front of a mirror in a totally dark room, and you will realize what we mean!

If you take a close look at any mirror, you would notice that it basically consists of a sheet of glass—large or small. What differentiates a mirror from an ordinary piece of glass is the coating of aluminum or silver on one side or on the back. And this coating is necessary; otherwise, how would you be able to see yourself or any other object in your mirror? For light falls on your face/body—then hits the mirror—the mirror throws it back—the light enters your eyes—you are able to see an “image”.

Now, this idea of backing a glass sheet with something did not originate till the 16th century. People belonging to the earlier Middle Ages, especially the Greco-Romans, observed themselves in hand-held disks of highly polished silver or bronze or tin! These disks were slightly convex in shape. The Venetians decided to experiment, and came up with the idea of a combination of mercury and tin (amalgam) to coat the surface of glass. This was replaced by metallic silver in 1835 (Justus von Liebig). And so the techniques of mirror-making kept advancing till modern times.

Take a look at the mirrors you have at home. You will notice that each one is coated with silver or aluminum. Are you aware of the process? It is not the result of painting with a hand-held brush. A thin layer of molten aluminum or silver is sputtered onto the back surface of the glass sheet or glass plate in a vacuum. If these mirrors are meant for use in an optical instrument such as a microscope, a telescope and so on, the aluminum is evaporated onto the front surface of the glass. This is to prevent faint reflections from the glass itself.

For a mirror to function properly, it must be allowed to reflect as much as possible the light falling on a body. The lesser the amount of light absorbed or transmitted, the clearer the image. You will understand this better with this example. Try looking at your face in the clear waters of a pond. Is the visualization so clean that you feel like you are looking into a mirror? Well then, the reflection of light is wonderful! Now, repeat the action with the rather cloudy waters of a pond or lake. Are you able to view a good image of yourself? If the answer is in the negative, then the light falling onto your body is being absorbed and not reflected.
When a mirror is manufactured, care is taken to ensure that the surface is perfectly smooth. If at all there are any irregularities, they are too miniscule to affect the functioning. Of course, the surface can be plane or curved (concave, convex). Again, the curved mirror can be of varying types—spherical (used as rearview mirrors for automobiles, facial makeup); cylindrical (to see upside-down images); paraboloidal (used in telescopes and searchlights); and ellipsoidal and hyperboloidal (used in other optical instruments).

 

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