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Which of the following statement is/are ...

Which of the following statement is/are true
(A)The resolution power of unaided human eye is 100 micrometre
(B) The highest resolution is obtained with the light of shortest wavelength
(C ) Dark fiel microscope is most useful for viewing the living cells
(D) In gel filtration chromatography, molecules can be separated in picogram to nanogram quantities

A

A, C and D only

B

B and D only

C

C and E only

D

A, B and D only

Text Solution

Verified by Experts

The correct Answer is:
D
*Under normal viewing conditions the resolving power of the human eye is approximately 100 micrometer.
* The highest resolution is obtained with the light having a short wavelength.
* Dark field describes an illumination technique used to enhance the contrast in unstained samples.
* Chromatography is the method of separating molecular components of the cell present in cytosol.
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The limit of resolution of a microscope is the least distance between two point objects which can be seen clearly and distinctively with it. For a naked eye, limit of resolution is about 10^(-4) m or 0.1 mm. The limit of resolution for a microscope is of the order of lambda/2 , where lambda is wavelength of light used. For an optical microscope , using visible light, limit of resolution is "500 nm"/2 =250 mm. This is 400 times smaller than naked eye. So the useful magnification produced by it is 400. Smaller is the limit of resolution, greater is the magnification that can be achieved. By using shorter wavelengths , we can improve resolution. For examination of a microorganism, much higher limit of resolution is needed, the Wave nature of electron provides a means for probes of very small size organisms. An electron beam accelerated by a high potential difference possess a very short wavelength. In an electron microscope magnetic lenses are used to control the path of electrons. The image of object is obtained on a fluorescent screen or on a photographic plate. The electron microscope with its high magnifying power and resolving power , is one of the most indispensable and powerful tool for research in science , medicine and industry. The advantage of electron microscope over optical microscope is that

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