Question

The numerical aperture of objective of a microscope is $0.12$. The limit of resolution, when light of wavelength $6000\mathring{A}$ is used to view an object is:

• A. $0.25\times {10}^{-7}m$
• B. $2.5\times {10}^{-7}m$
• C. $25\times {10}^{-7}m$
• D. $250\times {10}^{-7}m$

Answer 1

Answer: (C)

$25\times {10}^{-7}m$

Resolving power of a microscope of objective with numerical aperture $NA$ for a light of wavelength $\lambda$ is given by:

$R=\frac{\lambda }{2NA}$

$=\frac{6000\times {10}^{-10}}{2\times 0.12}$

$=25\times {10}^{-7}m$