Question

Q1. If the image is formed at a distance of 50cm from the lens. At what distance from the lens is the object placed. Find the focal length and power of the lens used
Pls tell me what is the answer:-
Class 10th questions!​

Answer 1

Answer:

Distance of object from the mirror u=−50 cm

Distance of image from the mirror v=−10 cm

For lens, we know

f

1

​  

=  

v

1

​  

−  

u

1

​  

 

f

1

​  

=  

−10

1

​  

−  

−50

1

​  

 

f=−12.5cm

It is a concave lens.

Explanation:

Answer 2

Answer:

Same size of image is formed by a convex lens only when the object is placed at a distance u=2f from the optical center and image is also formed at distance 2f on other side of lens.

⟹2f=50

⟹f=25cm

P=

f(m)

1

​

=

0.25

1

​

⟹P=+4D

Explanation: