In which year electron microscope was invented ?

Define microscope.

An electron microscope uses electron accelerated by a voltage of 50kV. Determine the de-Broglie wavelengths associated with the electrons. If other factors (such as numerical aperture etc) are taken to be roughly the same how does the resolving power of electron microscope compare with that of an optical microscope which uses yellow light?

In which year, Nylon was made?

What are those structers which appear as "beads- on -string" in the chromosomes whne viewed under electron microscope?

What voltage must be applied to an electron microscope to produce electrons of wavelength 0.4 overset @A ?

The PCR technique was invented by :

In which year 'family Planning' was initiated in India.