What is concave mirror used as shaving mirror?
I will elaborate.
A concave mirror forms virtual, erect and magnified image of the object PROVIDED THAT THE OBJECT IS BETWEEN FOCUS AND POLE OF THE MIRROR !! A person who is shaving always keeps his face close to the mirror so that his face comes between pole and focus. Thus he is able to view an enlarged and erect image of his face.
If his face is beyond focus, it will form real and inverted image.
Most commonly used mirrors at home are flat. These are the mirrors most commonly found in bathrooms. They reflect light so that the image formed is of exactly the same size as the object. The other two types of mirrors are convex and concave (shaving/make-up mirrors).
Heres a diagram of a concave mirror.
As you can see, a concave mirrors are curved inward, therefore they reflect light inward to one focal point (F). Every mirror has a focus point where all the light that shines on the mirror will reflect back. The focal length (f) is the distance between the focal point and the centre of the mirror. Remember that the focal length depends not on how far away the object is from the mirror but how curved the mirror is!
Now the angle at which the incident ray reflects back from the mirror depends on where it strikes the mirror in the first place. The reflected light will all pass through the focal point and therefore the image appears closer than it actually is, while the reflections appear bigger than they really are.
I hope this answers your question.