Question

a concave mirror has a focal length of 10cm where should an object be placed in front of this concave mirror so as to obtain an image which is real and inverted and same size as the object

Answer 1

Given,

         focal length of mirror (f) = 10 cm

and object distance (u) = image distance (v)

we know that,

                       1/f = 1/v+1/u

                    ⇒1/10 = 1/u+1/u (∵f=10 and v=u)

                     ⇒1/10 = 2/u

                     ⇒u = 20

∴ the object should be placed 20 cm in front of the concave mirror to obtain an image which is real and inverted and size as the object

                   

Answer 2

Answer: focal length (f) =10cm

1/v+1/u=1/f

1/u+1/u=1/10 (since f=10 and v=u)

=2/u=1/10

U = 20

Explanation: