Question

A man is looking at a small object placed at his near point. Without altering the position of his eye or the object, he puts a simple microscope of magnifying power 5 X before his eyes. The angular magnification achieved is
(a) 5
(b) 2.5
(c) 1
(d) 0.2

Answer 1

The angular magnification achieved is 1.

Option (c) 1 is the correct answer.

Explanation:  

Given data in the question  :

h is the object's height  

u is the object's distance

(i.e)

u = 25 cm

D is nearest point (A man sees a small object placed near his point)

so,  

D = 25 cm

Now,  

We know that,

The angular magnification is,

                                               $\begin{equation}m=\frac{\frac{h}{u}}{\frac{h}{D}}\end$

Put the given values in above equation,              

                                               $\begin{equation}\mathrm{m}=\frac{\frac{h}{u}}{\frac{h}{25}}\end$

                                               $\begin{equation}m=\frac{\mathrm{h}}{25} \times \frac{25}{\mathrm{h}}\end$

                                               m = 1

Thus, the approved angular magnification is 1.

Answer 2

The angular magnification achieved is (c) 1.

Explanation:

Let height of object be h

Let object distance be u = 25 cm

Let near point be D = 25 cm

The magnification is given by the formula:

m = h/h'

Where,

h = Height of image

h' = Height of object

Now, the angular magnification is given as,

m = (h/u)/(h/D)

On substituting the values, we get,

m = (h/25)/(h/25)

m = (h/25) × (25/h)

∴ m = 1