Question

Draw a neat labelled ray diagram for refracting efracting telescope. Obtain the formula for its magnifying power.

Answer 1

magnifying power is defined as ratio of angle subtended β by the final image on the eye to the angle subtended α by the object on eye.

M=tanβ/tanα=β/α

or

M= -fo/fe  for comfortable view

= -f₀/fe [(1+fe/D)] for strained eye