Resolving Power(R.P.):

Resolving Power of an optical instrument is its ability to form separate images of two point objects lying close to each other.

1. Resolving Power of a microscope:

R.P = 2µÂ sinθ / λ

Or  R.P = 2ν sinθ / u

λ →Wavelength of light used to illuminate the object

μ→ Refractive index of the medium between object and the objective lens of the microscope.

θ →Half angle of the cone of light form the point object on to the objective lens of microscope.

 

Resolving Power of a telescope:

R.P. = D/1.22 λ

Or  R.P. = D ν/1.22c

λ →Wavelength of light used

D →Diameter of the objective lens of the telescope.

 

Light gathering power of a telescope or Intensity of the image or brightness of image:-  

Intensity of image of telescope (I) ∝ area of objective

∴ I∝D²                      D -->Diameter of objective lens of telescope.

1. Intensity Ratio or Brightness Ratio:

Intensity ratio =  Intensity of image of seen by telescope/ Intensity of image seen by naked eye

D →diameter of objective lens of telescope

d→ diameter of eye lens