Question

Mention the types of mirrors used as (i) rear view mirrors, (ii) shaving mirrors. List two reasons to justify your answers in each case.

Answer 1

Hint: Rear view mirrors need to produce a diminished image and should have a larger field of view so that far objects can be easily seen in the mirror. For shaving purposes a mirror should produce a magnified image so that details of the face can be seen.

Complete answer:
(i) Convex mirrors are used as rear view mirrors because
A. They produce virtual and erect images of the objects.
B. They have a wider field of view as they are curved outwards. Hence far objects appear closer in the mirror.
(ii) Concave mirrors are used as shaving mirrors because
A. Image formed is magnified so details of the object are clearly visible.
B. When the object is placed close to the mirror the image formed is virtual and erect.

Additional Information:
The concave and convex mirrors are two types of curved mirrors. Concave mirrors are used where we want to converge light and convex mirrors are used where we want to diverge the light. When light rays parallel to the principal axis coming from infinity fall on the surface of the concave mirror, it converges at a single point on the principal axis. This point is called ‘Focus of concave mirror. The focus is also referred to as simply focus or focal point. The concave mirror’s focal point lies in front of the mirror. The focus of convex mirrors lies behind the mirror therefore light appears to be diverging when it gets reflected from the convex mirror.

Note: As a convex mirror produces a diminished image of a far object, a driver can easily see large traffic behind him in a small mirror. In a concave mirror which is used as a shaving mirror when we hold the face closer to the mirror, an enlarged image is produced. It is easy to understand which type of mirror is used once you understood their principle of working.