Image Formation

Convex Mirror

There are only two possibilities of position of object in the case of a convex mirror, i.e. object at infinity and object between infinity and pole of a convex mirror.

Object at infinity: When the object is at the infinity, a point sized image is formed at principal focus behind the convex mirror.

Fig: Object at infinity

Properties of image: Image is highly diminished, virtual and erect.

Object between infinity and pole: When the object is between infinity and pole of a convex mirror, a diminished, virtual and erect image is formed between pole and focus behind the mirror.

Fig: Object between infinity and P

Properties of image: Image is diminished, virtual and erect.

Uses of Concave Mirror:

• As reflector in electric torch, head lights of vehicle, search light, etc. The source of light is put at the focus of the reflector, which produces a strong parallel beam of light, which helps in clear visibility.
• As shaving mirror to produce larger image of face to facilitate better viewing during shaving.
• Concave mirror is used by dentists to see larger image of teeth of the patient. When a tooth is placed between focus and pole, the concave mirror produces a magnified image of the tooth.
• As reflector in solar furnace. By using concave mirror in solar furnace the concentrated rays of sunlight is obtained at focus which produces enormous amount of heat because of concentration.

Uses of Convex Mirror:

• Convex mirror is used in rear view mirror of vehicles; so that the driver can see the traffic coming from behind. The field of view is widest in case of a convex mirror, which enables it to show a wider area from behind.
• Convex mirror is used on hairpin bends on the road; so that the driver can see the traffic approaching from another side of the bend.