Question

A magnifying glass of focal length 10 cm is used to read letters of thickness
0.5 mm held 8 cm away from the lens. Calculate the image size. How big will
the letters appear?​

Answer 1

Answer:

10 cm is the answer of this question

Answer 2

Given that,

f= +10 cm, u= -8 cm

From thin lens formula,

$\frac{1}{f}$= $\frac{1}{v} - \frac{1}{u}$

$\frac{1}{10} = \frac{1}{v} - \frac{1}{8}$

Therefore, v= 40 cm

M= $\frac{v}{u}$ = Image size h₁/ Image size h₂

40/8= h₁/ 0.5

h₁= 2.5 cm (5 times that of object)

M= D/u =25/8

∴ Image will appear to be 3.125 times bigger,

i.e., 3.1250 × 5= 1.5625 cm