question_answer

At what distance an object from a concave lens having focal length of 20 cm should be placed so that the lens forms an image at the distance of 10 cm from the lens?

A) \[-\,\,12cm\]

B) \[-\,\,20cm\]

C) \[-\,\,30cm\]

D)  \[-\,\,25cm\]

E)  None of these