Fig 12.12: Ray diagram for a concave mirror, object at F
The image is 1. Behind the mirror 2. Virtual 3. Erect 4. Magnified
Convex mirror
The image is always 1. Behind the mirror 2. Virtual 3. Erect 4. Diminished
Fig 12.13: Ray diagram for a concave mirror, object between F and P
Fig 12.14: Ray diagram for a convex mirror
SCIENCE,TECHNOLOGY & SOCIETY
Practical uses of spherical mirrors Concave • Dentists use a small concave mirror placed in the mouth to get a magnified image of the teeth.The mirror will have a small focal length; the teeth are positioned inside the focus so as to produce a magnified erect image. Shaving mirrors or make- up mirrors use the same principle, but have a longer focal length.
• Floodlights or projectors have their bulbs at the focus of the mirror so that the reflected light is parallel with the principal axis. Car headlights use the same principle.
Convex • Supermarkets often place convex mirrors in such a way that the owner can see shoppers in different aisles. Convex mirrors often form part of a car’s rearview mirror so as to widen the field of view of the driver. Convex mirrors are also very useful outside concealed entrances/driveways that lead out to busy main roads.
