Please answer this question?

enter image source here

1 Answer
Chirag Mehta
Mar 2, 2018

See below.

Explanation:

For a biconvex lens we generally take f=R/2 (by generally i'm actually refering to a 10th gradier in India like me and ujjwal who has asked this question)

Now, using lens maker formula
meritnation

1/f = (n-1)(1/R_1 -1/R_2)

In case R_1 =R_2
The formula becomes

1/f=(n-1)(2/R)

Generally, we are too ignorant about n (refractive index) and we eliminate (n-1) as 1, this is what we have to do here.

Here n-1=1 , you have to accept it for time being because of absence of proper details.

1/f=(1/R_1 -1/R_2) " " (R_2 =-oo)

1/f=1/R

mini physics
Now recall the ray diagrams , if object is at C the image will also be at C.

Now, since there is a mirror so to form image of object on object itself the object distance should be 10cm.
Answer =10cm

Related questions
Impact of this question
2637 views around the world
You can reuse this answer
Creative Commons License