PART III Truel False questions 33 points3 points each T F Na

PART III: Truel False questions (33 points-3 points each) (T F) Nanostructured materials exhibit different optical, electrical, chemical and biological properties due to nanosize. (T F-In bottom-up nanofabrication, a nanostructured pattern is made in a larger size and minimize to nanoscale at a later stage. (T F) Vacuum pumps are operational only in the viscous flow. (T F) In STM (Scanning Tunneling Microscopy), the tunneling current flows across the small gap that separates the tip from the sample. projector. (T F-Mean-free path becomes smaller as the pressure goes down. (T F) The resistance of Carbon Nanotubes is dependent of the length of the wire (T F) A good optical microscope can have any resolution between 1nm to 10nm. (T F) One bar is equal to one atmospheric pressure (T F) In Scanning Tunneling Microscopy (STM), the sample surface has to be conductive. (T F) In Transmission Electron Microscopy (TEM), the sample surface has to be nonconductive.

Solution

1)In bottom-up nanofabrication a nanostructured pattern is made in a larger size and minimise to nanoscale at a later stage.(T)

2)Nanostructured materials exhibit different chemical,electrical,biological,optical properties due to nanosize.(T)

3)vaccum pumps are operational only in viscous flow.(F).

different vaccum pumps are operational in different flows.

4)In STM the tunneling current flows across the small gap that separates the tip from the sample.(T)

5)A transmission electron microscope is analogous to a slide projector.(T)

A projector shines a beam of light through a slide, as the light passes through the slide, it is modulated by the contents of the slide. this transmitted beam is then projected into the viewing screen, forming an enlarged image of the slide. TEM works in the same way except that they shine a beam of electrons through a specimen.

6)Mean free path becomes smaller as the pressure goes down.(F)

because it increases as the pressure increases.Gas molecules are very close together. • Therefore, volume of the gas particles becomes significant.

7)The resistance of the carbon nanotubes is dependent of the length of the wire.(T)

resistance increases exponentially with length of the wire.

8)A good optical microscope can have any of the resolution between 1nm to 10nm.(F)

its resolution limit is around 250nm.

9)One bar is equal to approximately 0.987 atmospheric pressure not 1 atmospheric pressure.(F)

10)In scanning tunneling microscopy the sample surface has to be conductive.(T)

11)In transmission electron microscopy the sample surface has to be nonconductive.(F)

For nonconductive samples enviromental scanning electron microscope is used.