Question

3. Why are plane mirrors coated with either silver or aluminium on
one side?​

Answer 1

Answer:

The plane mirrors coated with either silver or aluminum on one side because to see the ones own image.

Hope it's helpful to you.

According to my point of view this is the correct answer.

Answer 2

A mirror is a mirror because of silver coating. Silver reflects light very efficiently to form a virtual image of the same size of the object when the glass is plane.

All mirrors whether plane or not, are coated with silver, and back with lead oxide.

Unknowingly you have given the answer yourself. “ To protect.” Silver layer is very thin and hence very vulnerable to damage, scratch and atmospheric corrosion etc. A thin layer of sliver gets tarnished due to atmospheric oxygen and sulpher dioxide very quickly. Lead oxide is easy to coat uniformly, cheap, strong enough to wear and tear, and resistant to atmospheric effects.

Last but not the least, it does not react with metallic silver, so the the silver layer, if the mirror is kept well, lasts for a very long period, even centuries.

hope this will help u