A half diminished virtual, erect image is formed 12 cm closer to mirror than the object, when the object is placed in front of a spherical mirror. What type of mirror is used and what is its focal length?

A half diminished virtual, erect image is formed 12 cm closer to the lens than the object when the object is placed in front of a spherical lens. What type of lens is used and what is its focal length?

A virtual, erect, thrice magnfiied image is formed on the same side of the lens as the object. The image is formed 12 cm behind the object. What type of lens is used and hwat is its focal length? Draw the scheme diagram.

An object is placed in front of the mirror. But the image is found to be formed behind the mirror. The image is

The magnification, of the virtual, erect image is found to be one for all positions of the object. The mirror is