Question

The lens of a simple magnifier has a focal length of 2.5 cm. Calculate the angular magnification produced when the image is at the least distance of distinct vision.

• A. 10
• B. 5
• C. 8
• D. 15

Answer 1

The correct option is A 10

Focal length of a magnifier
$f=2.5cm$

(a) At least distance of distant vision, Angular magnification
$=1+\frac{D}{f}=1+\frac{25cm}{2.5cm}$

$=11$

(b) At infinity, angular magnification

$=\frac{D}{f}=\frac{25cm}{2.5cm}=10$