MENU
Question -

Anelectron microscope uses electrons accelerated by a voltage of 50 kV. Determinethe de Broglie wavelength associated with the electrons. If other factors (suchas numerical aperture, etc.) are taken to be roughly the same, how does theresolving power of an electron microscope compare with that of an opticalmicroscope which uses yellow light?



Answer -

Electrons are accelerated by avoltage,┬аV┬а= 50 kV = 50 ├Ч 103┬аV

Charge on an electron,┬аe┬а=1.6 ├Ч 10тИТ19┬аC

Mass of an electron,┬аme┬а=9.11 ├Ч 10тИТ31┬аkg

Wavelength of yellow light = 5.9 ├Ч 10тИТ7┬аm

The kinetic energy of theelectron is given as:

E┬а=┬аeV

= 1.6 ├Ч 10тИТ19┬а├Ч 50 ├Ч 103

= 8 ├Ч 10тИТ15┬аJ

De Broglie wavelength isgiven by the relation:

This wavelength is nearly 105┬аtimesless than the wavelength of yellow light.

Theresolving power of a microscope is inversely proportional to the wavelength oflight used. Thus, the resolving power of an electron microscope is nearly 105┬аtimesthat of an optical microscope.


Comment(S)

Show all Coment

Leave a Comment

Free - Previous Years Question Papers
Any questions? Ask us!
×