Question

between which two points of a concave mirror should and object be pleased to obtain a magnification of - 3

Answer 1

A magnification of -3 means that the image is real, inverted and magnified. So the object should be placed between F (principal focus) and C (centre of curvature).

hope this will help you

Answer 2

As the magnification is -3 the negative sign indicates inverted image.

To get -3 the image size should be more than object size.

Therfore I

If we keep object between f and C,we can get -3 magnification.

Sorry if I'm wrong.