Question

The limit of resolution of an instrument is

• A. The ability to distinguish two close objects as distant
• B. The ability to distinguish two distant objects as close
• C. Can distinguish two or more distant objects as close
• D. None of the above

Answer 1

Answer: (A)

The ability to distinguish two close objects as distant

Resolving power or limit of resolution is the ability to distinguish two close objects as distinct. It is calculated by the formula 0.61 $\lambda$/ numerical aperture, where $\lambda$ is the wavelength of light and numerical aperture is the light collecting ability of lens. Actually after calculations the value comes out to be 0.5 $\lambda$ or one half the wavelength of illuminating light. The average wavelength of light used in microscopes is 500 - 600 nm. It gives a maximum resolution of 250 - 300 nm or 0.25 micrometer to 0.3 micrometer.