Question
Draw a labelled ray diagram of a refracting telescope. Define its magnifying power and write the expression for it.
Write two important limitations of a refracting telescope over a reflecting type telescope.
Solution
The labelled diagram of a refracting telescope is as shown below:
Magnification power is defined as the ratio of the angle () subtended by the final image on the eye to the angle () subtended by the object on eye.
The mathematical formula is given by,
Also, it is given by,
Limitations of refracting telescope over a reflecting telescope are:
(i) Image is not free from chromatic aberration and spherical aberration.
(ii) Aperture of the objective lens should be large for high resolving power.
