Experiment of finding the resolving power of the

Experiment of finding the resolving power of the telescope

Trisha Banerjee @ 2010

Telescope whose resolving power has to be find

mirror

Sp (2)

Circular scale


Design of experimental set up:-

light from the mercury lamp passes through a collimator C and then diffracted by a diffraction grating G ( to be mounted on the prism table just front of C) which forms first and second order spectra over both the sides of the incident beam. in fact both the C and the prism table are the parts of sp(1) whose telescope have been removed and replaced by an appx 1 m arm( called optical bench), which can be rotated by loosening the turn table screw sp(1) . Double slit D and the mirror M are to be mounted on the stands which can be slides over the optical bench . The optical can be adjusted in the direction of the first order spectrum formed by the grating so that the double slit be illuminated by it. the light emanated by the double slit is first reflected by the mirror M almost in the backward direction and then observed by the telescope T of sp(2) this arrangement not only makes possible to achieve a large distance of the telescope T from D but also facilitates the landing of the diffraction grating as well as the double slit while observing the image s of the D through the telescope. If the double slit is adjusted at a distance equal to the focal length of this lens it would virtually be at infinity from the telescope . The angular separation theta between the rays apparently coming from two virtual slits ( image of the double slit) must be equal to the angle suspended by the real slit at the pole of the lens . This angle can be directly measure d by the spectrometer. Trisha Banerjee @

2010


Mercury lamp

Diffraction grating

Convex lens ( large focal length)

Single slit




Moving microscope.( to see minute object by horizontal and vertical movement)


How to measure from microscope

Object is hold here and by well focusing we can got the reading.

Horizontal scale

Vertical scale


Procedure in brief:

1) finding the least count of the circular scale. 2) focusing from the grating to the mirror of first order left spectrum of particular to the yellow light on the telescope we see the circular airy disc due to circular aperture of the telescope. 3) now with the help of the convex lens and the double slit find the angle between the slit i.e. their position reading. 4) then take the single slit and just merge the two slit by decreasing the width of the single slit. and got the circular reading. 5) by the help of the microscope determine the width of the single slit.

6) then got the find reading by several calculations.

NOTE:- the width of the double slit should be equal . do the same procedure for violet light just move the turn table. Trisha Banerjee @

2010

Technology

Experiment of finding the resolving power of the