Question

A small object placed in front of a concave mirror gives an image that is real and four times the size

of object. When object is moved 10cm towards the mirror, a virtual image of the same

magnification is produced. Find the focal length of the mirro r​

Answer 1

Answer:

The spherical mirror can not be

convex because it does not form

real image (that can  be formed on a screen).

So, the mirror has to be

conceal. In case of concave mirror,  

the real image is formed if the

object distance greater than focal

length. For enlarged real image

the object should be placed  

between the center and focus of  

the mirror. The image formed

will be real, enlarged and inverted

so, the magnification will be -2.

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