Question

An object is placed at a distance of 30 cm from the
pole of a concave lens of focal length 15 cm. find the position of the image. what is it's magnificention. ​

Answer 1

Answer:

Explanation:

Formula:

v

1

​  

+  

u

1

​  

=  

f

1

​  

 

Given,

v

1

​  

+  

(−20)

1

​  

=  

15

1

​  

 

v

1

​  

=  

60

7

​  

⇒v=  

7

60

​  

 

v=8.57≈8.6cm

The image is formed behind the mirror at a distance of 8.6 cm  

m=  

h  

1

​  

 

h  

2

​  

 

​  

=−  

u

v

​  

 

→  

5

h  

2

​  

 

​  

=−  

20

8.57

​  

 

∴h  

2

​  

=2.175 cm

Thus the image is 2.175 cm high, virtual and erect.

Hence, this is the answer.