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n a

 - 4 dictionary results

n/a

 
Use n a in a Sentence
1. no account.
2. not applicable.

N.A.

 
1. National Army.
2. North America.
3. not applicable.
4. Microscopy. numerical aperture.

numerical aperture

 
–noun Microscopy.
a measure of the resolving power of a microscope, equal to the index of refraction of the medium in which the object is placed multiplied by the sine of the angle made with the axis by the most oblique ray entering the instrument, the resolving power increasing as the product increases. Abbreviation: N.A.
Origin:
1875–80
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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Medical Dictionary

Main Entry: nu·mer·i·cal aperture
Pronunciation: n(y)u-'mer-i-k&l-
Function: noun
: a number that indicates the resolving power of amicroscope objective and is equal to the product of the index of refraction of the medium (as immersion oil) in front of the objective and the sine of half the angle formed by two rays emanating fromthe object upon which the microscope is focused and entering the objective at either end of a diameter of the objective
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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