Give scientific reason: A simple microscope is used by watch repairers.

A simple microscope is an optical instrument made of double convex lenses. The working of a microscope is such that the light from a source is first reflected by a mirror towards the first lens which forms the magnified image of the object being viewed. But this magnified image is a further made incident on another lens which magnifies the image even more. Finally the light from the magnified image is reflected towards the eyepiece which is the point where the observer views the magnified image of the object.

A watch is a device which contains many small parts working together to provide the correct display of time. If something goes wrong in it or the watch stops working then in order to properly view those small working parts the watch repairer uses a simple microscope which is able to magnify those small parts to the extent that they can be viewed easily and repair can be done easily. Without a magnifying device, it is very difficult to work on the small parts of the watch. A simple microscope can be found at every watch repairers shop.