Question

What is the angular magnification of a telescope that has a100cm focal length objective and a2.50cm focal length eyepiece?

Short answer

The angular magnification is $-40$

Step-by-step solution

Concept Introduction

Magnification is the process of expanding something's perceived size rather than its true size. This expansion is measured by a numerical value known as "magnification." When this value is less than one, it denotes a size decrease, often known as minification or de-magnification.

Calculating the magnification for a thin lens

The angular magnification is supplied by, as we said before in the idea session.

$$\begin{gathered} M=\frac{\theta \text{'}}{\theta }=\frac{f_0}{f_e} \\ =-\frac{1m}{0.025m} \\ =-40 \end{gathered}$$

Therefore, the angular magnification is =-40.