Question

A telescope has an objective of focal length 50 cm and eyepiece of focal length 5 cm. The least distant of distinct vision is 25 cm. The telescope is focussed for distinct vision on a scale 200 cm away from the object. Calculate the magnification produced?
1)4
2)-8
3)+8
4)-2

Answer 1

The magnification of a telescope is given by formula

$$M= M_{ objective } × M_{ eyepiece } (1)$$

In our case, we have

$$M_{ objective } =\frac{-1}{3}$$

$$M_{ eyepiece } =6$$

Using (1) we get:

M=-2

Answer:

4)-2