Question

Transmission electron microscope has a resolution of

A) 2000 nanometer

B) 200 nanometer

C) 2 nanometer

D) 0.2 nanometer

Answer 1

Hint: Transmission electron microscope is similar to a compound light microscope. It is used to view ultrathin sections of tissues, molecules etc. It is not used for imaging living specimens as the sample has to be kept in vacuum.

Complete answer:

To answer this question, we must know about the working principle behind transmission electron microscopy.

TEM is the most powerful microscope which is similar to that of a compound light microscope which uses beams of electrons instead of light. It produces a highly magnified image i.e. the image can be magnified up to 2 million times that of a light microscope.

The term 'resolution' is used to describe the ability of a microscope to distinguish detail. Or in other words we can say that, this is the minimum distance at which two distinct points of a specimen can still be seen - either by the observer or the microscope camera - as separate entities.

Working principle-

>A beam of electrons is made to fall on the ultra thin sections of the sample. The electrons have a shorter wavelength of around 0.005nm. As the electron beam falls onto the specimen, the resolution power increases, increasing the wavelength of the electron transmission.

>Applications- It helps in characterisation of morphological features, composition and illustrating the crystal structure of molecules as it can magnify particles of about 0.2nm. It is used to see the detailed structure of the smallest particle including the virus. It is used in nanotechnology to study the nanoparticles.

Thus the correct answer is (D). Transmission electron microscope has a resolution of 0.2nm.

Note: The advantages of TEM is that it produces high quality images with maximum clarity. The image produced is permanent. The major disadvantages of TEM are that it is very big, sample preparation is very tedious and also expensive.