Question

The magnification of the image formed by convex lens is 5 if the object kept at a distance of 10 cm from the lens find focal length of the lens

Answer 1

Answer:

Explanation:

Given: convex lens of focal length 10cm.

To find the nature, position and magnification of the image formed for object placed at

According to the given criteria,

Focal length, f=10cm

object distance, u=−15cm i.e., between F and 2F

Applying lens maker formula,

f

1

​  

=  

v

1

​  

−  

u

1

​  

 

⟹  

10

1

​  

=  

v

1

​  

−  

−15

1

​  

 

⟹  

v

1

​  

=  

10

1

​  

−  

15

1

​  

 

⟹  

v

1

​  

=  

30

3−2

​  

 

⟹v=30cm

The image is formed on the other side of the lens at a distance of 30 cm.

Magnification, m=−  

u

v

​  

=−  

−15

30

​  

=−2