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.

Answer 1

It is defined as the ratio of the angle (β) subtended by the final image on the eye to the angle(α) subtended by the object on eye.

Limitations: (i) Image is not free from chromatic aberration and spherical aberration.
(ii) Aperture of the objective lens should be large for high resolving power.