Question

If numerical aperture of a microscope is increased then its

• A. resolving power remains constant
• B. resolving power becomes zero
• C. limit of resolution is decreased
• D. limit of resolution is increased

Answer 1

Answer: (C)

limit of resolution is decreased

Answer 2

Resolving limit of microscope is given by
$R L=\frac{\lambda}{2 \mu \sin \alpha}$
where, $\mu \sin \alpha$ is called numerical aperture [NA] and $\lambda=$ wavelength of light.
$\therefore \,\,\,\,\,\,\,R L=\frac{\lambda}{2(N A)}$
Hence, if numerical aperture of a microscope is increased, then its limit of resolution is decreased.