Why is it difficult to see objects smaller than 0.2 micrometers using a light microscope?

Light Microscopes can magnify at most about two thousand times and the smallest extent to which this kind (The original Kind) of microscope can see is. 2 micrometers hence we cannot see anything smaller than that with light microscope, to see smaller than that we have to use electron microscope which uses a focused beam of electrons instead of light.