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(a) Define the term ‘resolving power of a telescople’. How will the resolving power be effected with the increase in (i) Wavelength of light used. (ii) Diameter of the objective lens. Justify your answers.

(b) A screen is placed 80 cm from an object. The image of the object on the screen is formed by a convex lens placed between them at two different locations separated by a distance 20 cm. Determine the focal length of the lens.12

 

Answers (1)

a) Resolving power of a telescope is defined as the reciprocal of the smallest
the angular separation between two distinct objects whose image can be just
resolved by it

i) 

RP\propto\frac{1}{\lambda}

As wavelength increases, R.P. decreases

ii) As the diameter of the objective lens increases, R.P. increases

RP\propto D

b) 

\\F=\frac{D^2-x^2}{4D}\\F=\frac{80^2-20^2}{4\times80}=18.75cm

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Safeer PP

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