Question

An object placed at 20 cm from a concave mirror forms a real inverted image at a distance 40 cm from the concave mirror. Find the focal length of the concave mirror ​

Answer 1

Answer:

Explanation:   Image is inverted so magnification ratio should be negative.

Since the object size is double so magnification ratio m=−2

now the object distance from mirror  u=−12

So m=−  

u

v

​

 

−2=−  

−12

v

​

 

v=−24cm

image is formed at 24 cm from mirror in same direction of object.

Now be know  

f

1

​

=  

v

1

​

+  

u

1

​

 

f

1

​

=  

−24

1

​

+  

−12

1

​

 

f=−8cm

Answer 2

Explanation:

answer is in this photo ok

I think It will be helpful