Question

Consider a refracting telescope whose objective has a focal length of 1m and the eyepiece a focal length of 1cm, then the magnifying power of this telescope will be …….. 

Hint:

The magnifying power of a telescope is given by \( M = \frac{f_o}{f_e} \). Increasing the focal length of the objective or decreasing the focal length of the eyepiece increases magnification.

Answer 1

Step 1: Understanding the Magnifying Power of a Telescope 
- A refracting telescope consists of two lenses:
- The objective lens, which collects light and forms an image.
- The eyepiece lens, which magnifies the image formed by the objective. - The magnifying power (\( M \)) of a telescope in normal adjustment (final image at infinity) is given by: \[ M = \frac{f_o}{f_e} \] where:
- \( f_o \) = focal length of the objective lens,
- \( f_e \) = focal length of the eyepiece lens. 
Step 2: Substituting the Given Values 
- Given: - \( f_o = 1m = 100cm \), - \( f_e = 1cm \). \[ M = \frac{100}{1} = 100 \] 
Step 3: Conclusion 
Thus, the magnifying power of this telescope is 100.