Question

why the diameter of objective of microscope should be small? and state two advantages of reflecting tyoe telelscope over refracting tyoe telelscope?

Answer 1

The microscope is used in sighting small objects situated nearby. If aperture is large then light ray coming from object expands. So intensity becomes small. If aperture is small then light coming from object expends in small aperture, as a result object is seen more bright. So, aperture is kept small.
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