Question

At what distance from a concave mirror of focal length 25 CM should an object to be placed so that the image is equal to the size of the object.... Plz solve it by using formula 1/f = 1/u+1/v and also with the help of signs.

Answer 1

Question:

At what distance from a concave mirror of focal length 25 CM should an object to be placed so that the image is equal to the size of the object ?

Answer:

Object distance = 50 Centimeters

Method of Solution:

Note: Lens Formula shows that Relationship between object, image Distance and focal length of the mirror. 

Given:

Focal Length of Concave mirror = 25 Centimeters

We know that Focal Length = Radius of curvature ÷ 2

So, Radius of Curvature =25 × 2 = 50 Centimeters

Now, Note: if we placed an object at Centre of curvature then image will be displayed at same size of Image .

From Above description , We can Says that ," if object is Equal to image , For which that Distance will double to it's focal Length.

Hence, the object Distance should be 50 Centimeters from the pole of the mirror.

Answer 2

Given:

Focal Length of mirror = 25 Cm


We know that Focal Length =R/ 2


Radius of Curvature =25 × 2 = 50 Cm





We can Says that ,if object is Equal to image , For which that distance will be double to it's focal Length.


Therefore, the object Distance should be 50 Cm from the pole of the mirror.