How can you distinguish between plane,convex and concave mirror without touching them?

This can be done easily by studying the nature and size of the image and the relative movement of the mirror with respect to the image:

 

1. If the image is upright, of the same size as the object and it does not change in size when the mirror is moved, then the mirror is a plane mirror.
2. If the image is upright, magnified and it becomes inverted when the mirror is moved away from the face, then the mirror is a concave mirror.
3. If the image is upright and diminished and it remains upright when the mirror is moved away from the face, then the mirror is a convex mirror.