Question

Where should an object is placed to obtain the image twice of object of focal length 12cm in front of a concave mirror. ​

Answer 1

Answer:

The object must be at the centre of curvature of the mirror.

Answer 2

Given that,

Given that,Focal length of a concave mirror f=12cm

Given that,Focal length of a concave mirror f=12cmObject length h=4

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cm

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,  m=−uv=−f−(u)−f

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,  m=−uv=−f−(u)−f −u1=−12−u−12

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,  m=−uv=−f−(u)−f −u1=−12−u−12 12+u=−48

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,  m=−uv=−f−(u)−f −u1=−12−u−12 12+u=−48 u=−48−12

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,  m=−uv=−f−(u)−f −u1=−12−u−12 12+u=−48 u=−48−12 u=−60cm

Given that,Focal length of a concave mirror f=12cmObject length h=4Real image length h′=1cmWe know that,  m=−uv=−f−(u)−f −u1=−12−u−12 12+u=−48 u=−48−12 u=−60cmHence, the object distance is 60 cm