Question

a galilean telescope has an objective of 120mm focal length and an eye piece of 50mm focal length if image seen by a eye is 250mm from the eye piece, what is angular magnification

Answer 1

The magnification of the image is 0.6

Explanation:

Given as :

For Galilean telescope

The focal length of the objective lens = $f_o$ = 120  mm

The focal length of the eye piece lens = $f_e$ = 500  mm

The distance of the object = u = 250 mm

Let The magnification = m

According to question

As magnification is directly proportional to the focal length of the objective lens .

i.e  m ∝ $f_o$                  ............1

As magnification Inversely proportional to the focal length of the eye piece.

i.e  m ∝ $\dfrac{1}{f_e}$                ............2

From eq 1 and 2

m = $\dfrac{f_0}{f_2}$

Or,  m = $\dfrac{120}{200}$

∴    m = 0.6

So, The magnification of the image = m = 0.6

Hence, The magnification of the image is 0.6   Answer

Answer 2

Explanation:

The answer is m= 2.4

hope this is help you